📐 CBSE 2026–27 · Class 10 & 12

Complete Mathematics
Formula Compendium

All Chapters · Maximum Formulas · Every Twisted Form

Akshit Tyagi
Made by Akshit Tyagi CBSE Mathematics Reference · 2026–27
3Parts
27+Chapters
300+Formulas
Class 10 & 12Syllabus
📐 CBSE Mathematics Formula Compendium 2026–27
📖 How to Use: Every formula is presented in its standard form, rearranged forms, special cases, and derived identities so you can tackle any exam question from any angle. Use the sidebar to navigate chapters quickly.
🎯 Part A
Class 10 Mathematics
01
Real Numbers
1.1 Euclid's Division Lemma
a = bq + r, where 0 ≤ r < b → b = (a - r) / q → q = (a - r) / b → r = a - bq → a - r = bq → a mod b = r
1.2 HCF & LCM Relationship
HCF(a, b) × LCM(a, b) = a × b → LCM(a, b) = (a × b) / HCF(a, b) → HCF(a, b) = (a × b) / LCM(a, b) → a = HCF × (a/HCF) → b = HCF × (b/HCF) → LCM = HCF × (a/HCF) × (b/HCF) For three numbers: HCF(a,b,c) × LCM(a,b,c) ≠ a×b×c [NOT directly] LCM(a,b,c) = (a×b×c × HCF(a,b,c)) / [HCF(a,b) × HCF(b,c) × HCF(a,c)]
1.3 Fundamental Theorem of Arithmetic
Every composite number = product of primes (unique, order aside) n = p₁^a₁ × p₂^a₂ × p₃^a₃ × ... × pₖ^aₖ HCF = product of SMALLEST powers of common prime factors LCM = product of GREATEST powers of all prime factors
1.4 Rational & Irrational Numbers
Rational number p/q terminates iff q = 2^m × 5^n Number of decimal places = max(m, n) If q has prime factor other than 2 or 5 → non-terminating repeating √p is irrational if p is a prime number √(a/b) is irrational if a/b is not a perfect square of rationals
1.5 Divisibility Conditions
n² - 1 = (n-1)(n+1) n(n+1) = always even n(n+1)(n+2) = always divisible by 6 n(n+1)(2n+1)/6 = sum of squares of first n natural numbers
1.6 Key Number Theory Identities
(a + b)² = a² + 2ab + b² (a - b)² = a² - 2ab + b² a² - b² = (a+b)(a-b) (a + b)³ = a³ + 3a²b + 3ab² + b³ (a - b)³ = a³ - 3a²b + 3ab² - b³ a³ + b³ = (a+b)(a² - ab + b²) a³ - b³ = (a-b)(a² + ab + b²) Twisted Forms: ab = [(a+b)² - a² - b²] / 2 ab = [(a+b)² - (a-b)²] / 4 a² + b² = (a+b)² - 2ab a² + b² = (a-b)² + 2ab (a+b)² - (a-b)² = 4ab (a+b)² + (a-b)² = 2(a²+b²)
02
Polynomials
2.1 Degree and Types
Linear: ax + b = 0 (degree 1) → 1 zero Quadratic: ax² + bx + c = 0 (degree 2) → 2 zeros Cubic: ax³+bx²+cx+d = 0 (degree 3) → 3 zeros
2.2 Quadratic Polynomial — Relationship Between Zeros and Coefficients
p(x) = ax² + bx + c, zeros: α, β Sum of zeros: α + β = -b/a Product of zeros: α × β = c/a → b = -a(α + β) → c = a(α × β) → a/b = -1/(α+β) → b/c = -(α+β)/(αβ) Twisted Derived Forms: α² + β² = (α+β)² - 2αβ = b²/a² - 2c/a = (b² - 2ac)/a² (α - β)² = (α+β)² - 4αβ = b²/a² - 4c/a = (b² - 4ac)/a² |α - β| = √[(α+β)² - 4αβ] = √(b²-4ac) / |a| α² - β² = (α+β)(α-β) 1/α + 1/β = (α+β)/(αβ) = -b/c 1/(αβ) = a/c α/β + β/α = (α²+β²)/(αβ) = (b²-2ac)/(ac) α² × β² = (αβ)² = c²/a² α³ + β³ = (α+β)³ - 3αβ(α+β) = (-b/a)³ - 3(c/a)(-b/a) = (-b³ + 3abc) / a³ α³ - β³ = (α-β)[(α+β)²-αβ] 1/α² + 1/β² = (α²+β²)/(αβ)² = (b²-2ac)/c² (α+1)(β+1) = αβ + α + β + 1 = c/a - b/a + 1 = (c - b + a)/a (α-1)(β-1) = αβ - (α+β) + 1 = c/a + b/a + 1 = (c + b + a)/a α²β + αβ² = αβ(α+β) = (c/a)(-b/a) = -bc/a²
2.3 Formation of Quadratic from Given Zeros
p(x) = x² - (α+β)x + αβ [when a=1] p(x) = k[x² - (α+β)x + αβ] [general, k ≠ 0] p(x) = k[x² - (sum of zeros)x + (product of zeros)]
2.4 Cubic Polynomial — Relationship with Zeros
p(x) = ax³ + bx² + cx + d, zeros: α, β, γ α + β + γ = -b/a αβ + βγ + γα = c/a αβγ = -d/a Twisted Forms: α² + β² + γ² = (α+β+γ)² - 2(αβ+βγ+γα) = b²/a² - 2c/a = (b²-2ac)/a² α³+β³+γ³-3αβγ = (α+β+γ)(α²+β²+γ²-αβ-βγ-γα) 1/α + 1/β + 1/γ = (αβ+βγ+γα)/(αβγ) = -c/d Formation: p(x) = x³ - (α+β+γ)x² + (αβ+βγ+γα)x - αβγ
2.5 Division Algorithm
Dividend = Divisor × Quotient + Remainder p(x) = g(x) × q(x) + r(x) where deg[r(x)] < deg[g(x)] → p(x) - r(x) = g(x) × q(x) [p-r is divisible by g] → q(x) = [p(x) - r(x)] / g(x)
2.6 Discriminant (Δ)
Δ = b² - 4ac Δ > 0 → two distinct real zeros Δ = 0 → two equal real zeros (coincident) Δ < 0 → no real zeros (complex) Zeros: α, β = [-b ± √(b²-4ac)] / 2a [Quadratic Formula] → α + β = -b/a (verify) → α - β = √Δ / a (difference of roots) → 2α = (-b/a) + √Δ/a = (-b + √Δ)/a → 2β = (-b/a) - √Δ/a = (-b - √Δ)/a
03
Pair of Linear Equations in Two Variables
3.1 Standard Form
a₁x + b₁y + c₁ = 0 a₂x + b₂y + c₂ = 0
3.2 Consistency Conditions
Unique solution (consistent): a₁/a₂ ≠ b₁/b₂ Infinitely many (consistent): a₁/a₂ = b₁/b₂ = c₁/c₂ No solution (inconsistent): a₁/a₂ = b₁/b₂ ≠ c₁/c₂
3.3 Cross-Multiplication Method
x y 1 ——————— = ——————— = ———————— b₁c₂-b₂c₁ c₁a₂-c₂a₁ a₁b₂-a₂b₁ → x = (b₁c₂ - b₂c₁) / (a₁b₂ - a₂b₁) → y = (c₁a₂ - c₂a₁) / (a₁b₂ - a₂b₁) Let D = a₁b₂ - a₂b₁ Dx = b₁c₂ - b₂c₁ [replace a-column with c values, negated] Dy = c₁a₂ - c₂a₁ x = Dx/D, y = Dy/D
3.4 Substitution Method (Steps)
From eq1: y = (c₁ - a₁x) / b₁ Substitute in eq2: a₂x + b₂[(c₁-a₁x)/b₁] + c₂ = 0 Solve for x, then back-substitute for y
3.5 Elimination Method
Multiply eq1 by a₂, eq2 by a₁: a₁a₂x + b₁a₂y = -c₁a₂ a₁a₂x + b₂a₁y = -c₂a₁ Subtract: y(b₁a₂ - b₂a₁) = c₂a₁ - c₁a₂ → y = (c₂a₁ - c₁a₂)/(b₁a₂ - b₂a₁)
3.6 Graphical Interpretation
Lines intersect → unique solution → (x,y) = point of intersection Lines parallel → no solution → slopes equal, y-intercepts differ Lines coincident → infinite solutions → same line Slope of a₁x + b₁y + c₁ = 0 is m = -a₁/b₁
04
Quadratic Equations
4.1 Standard Form & Quadratic Formula
ax² + bx + c = 0 (a ≠ 0) x = [-b ± √(b² - 4ac)] / 2a x₁ = (-b + √D) / 2a x₂ = (-b - √D) / 2a where D = b² - 4ac (Discriminant)
4.2 Nature of Roots
D > 0 → two distinct real roots D = 0 → two equal real roots: x = -b/2a D < 0 → no real roots (imaginary) D is perfect square → rational roots D > 0 but not perfect square → irrational roots
4.3 Sum and Product of Roots
x₁ + x₂ = -b/a x₁ × x₂ = c/a x₁ - x₂ = √D/a = √(b²-4ac)/a Equation from roots: x² - (x₁+x₂)x + x₁x₂ = 0
4.4 Completing the Square
ax² + bx + c = 0 x² + (b/a)x + c/a = 0 (x + b/2a)² = b²/4a² - c/a = (b²-4ac)/4a² x + b/2a = ± √(b²-4ac) / 2a x = -b/2a ± √(b²-4ac)/2a
4.5 Special Cases & Factoring Tricks
If sum of coefficients = 0: x=1 is always a root i.e., a + b + c = 0 → x=1 and x=c/a If a + c = b: x = -1 is always a root For x² - Sx + P = 0: roots are S±√(S²-4P)/2 Factoring: ax²+bx+c = a(x-x₁)(x-x₂) = a[x² - (x₁+x₂)x + x₁x₂]
4.6 Common Root Condition
If ax²+bx+c=0 and dx²+ex+f=0 share a common root r: ar²+br+c=0 and dr²+er+f=0 → r = (bf-ce)/(cd-af) = (ae-bd)/(bf-ce) [cross multiply] Condition: (bf-ce)(ae-bd) = (cd-af)²
05
Arithmetic Progressions (AP)
5.1 General Term (nth Term)
aₙ = a + (n-1)d where: a = first term d = common difference = aₙ - aₙ₋₁ n = number of terms → n = (aₙ - a)/d + 1 → d = (aₙ - a)/(n-1) → a = aₙ - (n-1)d → aₙ = l = last term Last term: l = a + (n-1)d Number of terms: n = (l-a)/d + 1
5.2 Sum of n Terms
Sₙ = n/2 [2a + (n-1)d] Sₙ = n/2 [a + l] (when last term l is known) Sₙ = n/2 [a + aₙ] → aₙ = Sₙ - Sₙ₋₁ (nth term from sum) → 2a + (n-1)d = 2Sₙ/n → d = 2(Sₙ - na) / [n(n-1)] → a = [2Sₙ - n(n-1)d] / 2n If Sₙ = An² + Bn: aₙ = A(2n-1) + B (nth term) a₁ = A + B d = 2A
5.3 Important Sum Formulas
Sum of first n natural numbers: Σn = n(n+1)/2 Sum of first n odd numbers: 1+3+5+...+(2n-1) = n² Sum of first n even numbers: 2+4+6+...+2n = n(n+1) Sum of squares of first n naturals: Σn² = n(n+1)(2n+1)/6 Sum of cubes of first n naturals: Σn³ = [n(n+1)/2]²
5.4 Arithmetic Mean
AM between a and b: A = (a+b)/2 → a, A, b are in AP ↔ A-a = b-A ↔ 2A = a+b n AMs between a and b: A₁ = a + d, A₂ = a + 2d, ..., Aₙ = a + nd where d = (b-a)/(n+1) Sum of n AMs between a and b = n(a+b)/2
5.5 Properties of AP
If a, b, c are in AP: 2b = a + c → b-a = c-b If each term multiplied by k → still AP with same ratio If constant added → still AP with same d If reversed → still AP with common difference -d aₘ + aₙ = aₚ + aₚ where m+n = p+q (same sum of indices → same sum of terms) Middle term of AP with odd n = Sₙ/n = average 3 numbers in AP: a-d, a, a+d [sum = 3a] 4 numbers in AP: a-3d, a-d, a+d, a+3d [sum = 4a] 5 numbers in AP: a-2d, a-d, a, a+d, a+2d [sum = 5a]
5.6 Twisted AP Identities
aₘ - aₙ = (m-n)d aₘ/aₙ = [a+(m-1)d] / [a+(n-1)d] If aₘ = n and aₙ = m: d = (n-m)/(m-n) = -1 aₘ₊ₙ = 0 If Sₘ/Sₙ = (am+b)/(cm+d) [ratio of sums given]: aₘ/aₙ = [a(2m-1)+b] / [c(2m-1)+d] [replace n by 2n-1] Sₘ = Sₙ (m≠n) → Sₘ₊ₙ = 0 → aₘ₊ₙ₊₁ = 0
06
Triangles
6.1 Basic Proportionality Theorem (Thales' Theorem)
If DE ∥ BC in △ABC, D on AB, E on AC: AD/DB = AE/EC Equivalent Forms: AD/AB = AE/AC (part/whole ratio) DB/AB = EC/AC AB/AD = AC/AE AB/DB = AC/EC DB/AD = EC/AE
6.2 Converse of BPT
If AD/DB = AE/EC, then DE ∥ BC
6.3 Angle Bisector Theorem
If AD bisects ∠A in △ABC: BD/DC = AB/AC → BD = (AB × BC)/(AB + AC) → DC = (AC × BC)/(AB + AC)
6.4 Criteria for Similarity
AAA / AA: two pairs of equal angles → similar SSS: all three sides proportional → similar SAS: two sides proportional and included angle equal → similar If △ABC ~ △DEF: AB/DE = BC/EF = CA/FD = k (scale factor) ∠A = ∠D, ∠B = ∠E, ∠C = ∠F
6.5 Properties of Similar Triangles
If △ABC ~ △DEF with ratio k: Ratio of perimeters = k = AB/DE Ratio of areas = k² = (AB/DE)² Ratio of altitudes = k Ratio of medians = k Ratio of angle bisectors = k Ratio of circumradii = k Ratio of inradii = k Area(△ABC)/Area(△DEF) = (AB/DE)² = (BC/EF)² = (CA/FD)²
6.6 Pythagoras Theorem & Converse
In right △ABC (right angle at C): AB² = BC² + AC² (Hypotenuse)² = (Base)² + (Perpendicular)² → BC² = AB² - AC² → AC² = AB² - BC² → BC = √(AB² - AC²) Converse: If AB² = BC² + AC², then ∠C = 90° Pythagorean Triplets (a,b,c) where a²+b²=c²: (3,4,5), (5,12,13), (8,15,17), (7,24,25), (9,40,41) (6,8,10), (10,24,26) [multiples of above] General: (m²-n², 2mn, m²+n²) for m>n>0
6.7 Important Results from Pythagoras
In △ABC, if altitude CD ⊥ AB: CD² = AD × DB [geometric mean relation] BC² = BD × BA [altitude on hypotenuse] AC² = AD × AB CD = (AC × BC)/AB Median formula (in △ABC, m_a = median from A): m_a² = (2b² + 2c² - a²)/4 Stewart's Theorem: b²m + c²n - a(mn + d²) = 0 [cevian d divides BC into m and n]
6.8 Congruence Criteria
SSS: three sides equal SAS: two sides and included angle equal ASA: two angles and included side equal AAS: two angles and non-included side equal RHS: right angle, hypotenuse, one side equal
07
Coordinate Geometry
7.1 Distance Formula
d = √[(x₂-x₁)² + (y₂-y₁)²] → d² = (x₂-x₁)² + (y₂-y₁)² → (x₂-x₁)² = d² - (y₂-y₁)² Distance from origin O(0,0) to P(x,y): d = √(x² + y²) Distance between P(x₁,y₁) and Q(x₂,y₂): PQ = √[(x₁-x₂)² + (y₁-y₂)²]
7.2 Section Formula
Point P dividing A(x₁,y₁) and B(x₂,y₂) in ratio m:n INTERNAL division: P = [(mx₂ + nx₁)/(m+n), (my₂ + ny₁)/(m+n)] EXTERNAL division: P = [(mx₂ - nx₁)/(m-n), (my₂ - ny₁)/(m-n)] Finding ratio m:n given P(x,y) on AB: m/n = (x - x₁)/(x₂ - x) [using x-coordinate] m/n = (y - y₁)/(y₂ - y) [using y-coordinate]
7.3 Midpoint Formula
Midpoint M of A(x₁,y₁) and B(x₂,y₂): M = [(x₁+x₂)/2, (y₁+y₂)/2] → x₁ + x₂ = 2xₘ → x₁ = 2xₘ - x₂ [find other endpoint if midpoint known]
7.4 Centroid of Triangle
G = [(x₁+x₂+x₃)/3, (y₁+y₂+y₃)/3] → x₁+x₂+x₃ = 3xG → If G = (0,0): x₁+x₂+x₃ = 0, y₁+y₂+y₃ = 0
7.5 Area of Triangle
Area = ½ |x₁(y₂-y₃) + x₂(y₃-y₁) + x₃(y₁-y₂)| Expanded: = ½ |x₁y₂ - x₁y₃ + x₂y₃ - x₂y₁ + x₃y₁ - x₃y₂| Shoelace form: = ½ |(x₁y₂ - x₂y₁) + (x₂y₃ - x₃y₂) + (x₃y₁ - x₁y₃)| Collinearity condition (Area = 0): x₁(y₂-y₃) + x₂(y₃-y₁) + x₃(y₁-y₂) = 0
7.6 Slope of a Line
m = (y₂-y₁)/(x₂-x₁) = tan θ → θ = arctan(m) (angle with positive x-axis) Parallel lines: m₁ = m₂ Perpendicular: m₁ × m₂ = -1 → m₂ = -1/m₁ Slope-intercept form: y = mx + c Point-slope form: y - y₁ = m(x - x₁) Two-point form: (y-y₁)/(y₂-y₁) = (x-x₁)/(x₂-x₁) Intercept form: x/a + y/b = 1
7.7 Area of Quadrilateral & Polygon
Area of quadrilateral ABCD: = ½ |d₁ × d₂ × sin θ| (diagonals d₁, d₂ at angle θ) Or using vertices A,B,C,D: = ½ |(x₁-x₃)(y₂-y₄) - (x₂-x₄)(y₁-y₃)| [diagonals AC, BD] Using Shoelace: = ½ |(x₁y₂-x₂y₁) + (x₂y₃-x₃y₂) + (x₃y₄-x₄y₃) + (x₄y₁-x₁y₄)|
7.8 Key Distance Facts
Collinear: AB + BC = AC (if B is between A and C) Isosceles: two distances equal Equilateral: all three distances equal, each = same Right angle: (longest)² = (other)² + (other)² Rectangle: diagonals equal and bisect each other Rhombus: all sides equal, diagonals bisect perpendicularly Square: all sides equal + diagonals equal Parallelogram: diagonals bisect each other (midpoints same)
08–09
Trigonometry & Applications
8.1 Trigonometric Ratios (Right Triangle)
sin θ = Opposite/Hypotenuse = P/H cos θ = Adjacent/Hypotenuse = B/H tan θ = Opposite/Adjacent = P/B cosec θ = 1/sin θ = H/P sec θ = 1/cos θ = H/B cot θ = 1/tan θ = B/P = cos θ/sin θ tan θ = sin θ/cos θ cot θ = cos θ/sin θ
8.2 Reciprocal Relations
sin θ × cosec θ = 1 → cosec θ = 1/sin θ cos θ × sec θ = 1 → sec θ = 1/cos θ tan θ × cot θ = 1 → cot θ = 1/tan θ
8.3 Pythagorean Identities
sin²θ + cos²θ = 1 ← PRIMARY → sin²θ = 1 - cos²θ → cos²θ = 1 - sin²θ → sinθ = √(1-cos²θ) → cosθ = √(1-sin²θ) 1 + tan²θ = sec²θ ← SECONDARY → sec²θ - tan²θ = 1 → sec²θ - 1 = tan²θ → tan²θ = sec²θ - 1 → (secθ + tanθ)(secθ - tanθ) = 1 → secθ + tanθ = 1/(secθ - tanθ) 1 + cot²θ = cosec²θ ← TERTIARY → cosec²θ - cot²θ = 1 → cosec²θ - 1 = cot²θ → (cosecθ + cotθ)(cosecθ - cotθ) = 1 → cosecθ + cotθ = 1/(cosecθ - cotθ)
8.4 Standard Angle Values Table
Angle θ: 0° 30° 45° 60° 90° ───────────────────────────────────────────────────── sin θ: 0 1/2 1/√2 √3/2 1 cos θ: 1 √3/2 1/√2 1/2 0 tan θ: 0 1/√3 1 √3 ∞ cosec θ: ∞ 2 √2 2/√3 1 sec θ: 1 2/√3 √2 2 ∞ cot θ: ∞ √3 1 1/√3 0 Memory trick for sin: √0/2, √1/2, √2/2, √3/2, √4/2 = 0, 1/2, 1/√2, √3/2, 1
8.5 Complementary Angle Relations
sin(90°-θ) = cosθ → cosθ = sin(90°-θ) cos(90°-θ) = sinθ → sinθ = cos(90°-θ) tan(90°-θ) = cotθ → cotθ = tan(90°-θ) cot(90°-θ) = tanθ → tanθ = cot(90°-θ) sec(90°-θ) = cosecθ → cosecθ = sec(90°-θ) cosec(90°-θ) = secθ → secθ = cosec(90°-θ)
8.6 Useful Identity Proofs (Templates)
(sinθ + cosθ)² = 1 + 2sinθcosθ (sinθ - cosθ)² = 1 - 2sinθcosθ (sinθ + cosθ)² + (sinθ - cosθ)² = 2 sin⁴θ + cos⁴θ = 1 - 2sin²θcos²θ = 1 - 2sin²θ(1-sin²θ) sin⁶θ + cos⁶θ = 1 - 3sin²θcos²θ tanθ + cotθ = 1/(sinθcosθ) = secθcosecθ tanθ - cotθ = (sin²θ-cos²θ)/(sinθcosθ) = -cos2θ/(sinθcosθ) secθ + tanθ = (1+sinθ)/cosθ secθ - tanθ = (1-sinθ)/cosθ = 1/(secθ+tanθ) cosecθ + cotθ = (1+cosθ)/sinθ cosecθ - cotθ = (1-cosθ)/sinθ = 1/(cosecθ+cotθ)
8.7 Heights and Distances (Chapter 9)
Angle of Elevation: angle from horizontal UP to object Angle of Depression: angle from horizontal DOWN to object tan(angle of elevation) = Height / Horizontal Distance tan(angle of depression) = Height / Horizontal Distance Height h = d × tan θ Distance d = h / tan θ = h × cot θ If angle of elevation from A is α, from B (further) is β: (α > β since A is closer) Let AB = x, object height = h, base of object foot = C h/BC = tan α → BC = h/tanα = h cotα h/AC = tan β → AC = h cotβ AB = AC - BC = h(cotβ - cotα) → h = AB/(cotβ - cotα) = AB tanα tanβ/(tanα - tanβ) Two buildings problem: Height of taller - shorter = d × (tanα - tanβ) [careful about geometry]
10
Circles
10.1 Tangent Properties
Tangent ⊥ radius at point of contact Length of tangent from external point P to circle (center O, radius r): PQ = PT = √(PO² - r²) → PO² = PQ² + r² (Pythagoras) → r² = PO² - PQ² Tangents from same external point are equal: PA = PB (A,B are points of tangency)
10.2 Angle Properties of Tangent
∠OAP = ∠OBP = 90° (tangent-radius angle) In quadrilateral OAPB (P external, A,B tangent points): ∠APB + ∠AOB = 180° [opposite angles supplementary] ∠APO = ∠BPO [OP bisects angle between tangents] ∠AOT = ∠BOT [OP bisects angle between radii] OA = OB = r PA = PB OP = OP (common) → △OAP ≅ △OBP (RHS congruence)
10.3 Circle Theorems
Angle in semicircle = 90° Angles in same segment are equal Angle at center = 2 × angle at circumference (same arc) Opposite angles of cyclic quadrilateral sum to 180° Exterior angle of cyclic quadrilateral = interior opposite angle Equal chords subtend equal angles at center Perpendicular from center to chord bisects the chord
10.4 Chord-Tangent Angle
Angle between tangent and chord = angle in alternate segment (Tangent-chord angle = inscribed angle on opposite side)
11
Areas Related to Circles
11.1 Basic Circle Formulas
Area of circle = πr² Circumference = 2πr = πd Diameter d = 2r Area = π(d/2)² = πd²/4 r = √(Area/π) r = Circumference/(2π)
11.2 Sector Formulas
Area of sector = (θ/360°) × πr² [θ in degrees] = (1/2)r²θ [θ in radians] = (1/2) × l × r [l = arc length] Arc length = (θ/360°) × 2πr = (θ/180°) × πr = rθ [θ in radians] Perimeter of sector = 2r + l = 2r + (θ/360°)×2πr = 2r + (πrθ/180°) → r = 2 × Area / l [from A = ½lr] → θ = (l/r) radians = (l/r) × (180°/π) degrees
11.3 Segment Formulas
Area of minor segment = Area of sector - Area of triangle = (θ/360°)πr² - (1/2)r² sin θ = r²[(πθ/360°) - (sinθ/2)] = (r²/2)[θ_rad - sinθ] [θ in radians] Area of major segment = πr² - Area of minor segment Chord length = 2r sin(θ/2) Height of segment = r(1 - cosθ/2) = r - r cos(θ/2)
11.4 Combination Formulas
Area of ring (annulus) = π(R²-r²) = π(R+r)(R-r) where R=outer radius, r=inner radius Area of semi-circle = πr²/2 Perimeter of semi-circle = πr + 2r = r(π+2) Area of quadrant = πr²/4 Perimeter of quadrant = πr/2 + 2r = r(π/2 + 2) Shaded region problems: Area of figure = Area₁ ± Area₂ ± Area₃...
12
Surface Areas and Volumes
12.1 Cuboid
LSA (Lateral Surface Area) = 2h(l+b) TSA (Total Surface Area) = 2(lb + bh + hl) Volume = l × b × h Diagonal = √(l²+b²+h²) Face diagonal (on lb face) = √(l²+b²) → l = V/(bh) → LSA = TSA - 2lb [remove top and bottom]
12.2 Cube (side = a)
LSA = 4a² TSA = 6a² Volume = a³ Diagonal = a√3 Face diagonal = a√2 → a = (V)^(1/3) → a = √(TSA/6)
12.3 Cylinder (radius r, height h)
CSA (Curved SA) = 2πrh TSA = 2πr(r+h) = 2πr² + 2πrh Volume = πr²h → r = CSA/(2πh) → h = CSA/(2πr) → h = V/(πr²) → r = √(V/πh) → r+h = TSA/(2πr) [if r known]
12.4 Cone (radius r, height h, slant l)
Slant height l = √(r²+h²) CSA = πrl = πr√(r²+h²) TSA = πrl + πr² = πr(l+r) Volume = (1/3)πr²h → h = √(l²-r²) → r = √(l²-h²) → l = √(r²+h²) → r = CSA/(πl) → h = 3V/(πr²) → r = √(3V/(πh))
12.5 Sphere (radius r)
SA (Surface Area) = 4πr² Volume = (4/3)πr³ → r = √(SA/4π) → r = (3V/4π)^(1/3) → V = (SA)^(3/2) / (6√π) [from eliminating r] → SA³ = 36π V² [classic relation]
12.6 Hemisphere (radius r)
CSA = 2πr² TSA = 3πr² [CSA + base circle πr²] Volume = (2/3)πr³ → r = √(CSA/2π) → r = √(TSA/3π) → r = (3V/2π)^(1/3)
12.7 Frustum of Cone (R=bigger radius, r=smaller, h=height, l=slant)
Slant height l = √[h² + (R-r)²] CSA = π(R+r)l TSA = π(R+r)l + πR² + πr² = π[(R+r)l + R² + r²] Volume = (πh/3)(R² + r² + Rr) → h = 3V / [π(R²+r²+Rr)] → l = √[h²+(R-r)²] When r=0 → cone: V = πR²h/3 ✓ When r=R → cylinder: V = πR²h ✓
12.8 Combination of Solids
Total Volume = V₁ + V₂ + ... Total SA = SA of outer surface only (remove hidden parts) Hemisphere on cylinder: TSA = CSA of cylinder + CSA of hemisphere + base circle = 2πrh + 2πr² + πr² = πr(2h + 3r) Volume = πr²h + (2/3)πr³ = πr²(h + 2r/3) Cone on cylinder: TSA = base of cylinder + CSA cylinder + CSA cone = πr² + 2πrh + πrl Volume = πr²H + (1/3)πr²h_cone
12.9 Volume Conversion Formulas
If solid A melted and recast into solid B: Volume of A = Volume of B (if no wastage) n × Volume of B = Volume of A (n pieces of B from A) If melted cube of side a → n spheres of radius r: a³ = n × (4/3)πr³ → n = 3a³/(4πr³) → r = a × (3/4πn)^(1/3)
13
Statistics
13.1 Mean (Ungrouped)
x̄ = (x₁+x₂+...+xₙ)/n = Σxᵢ/n = Σfᵢxᵢ/Σfᵢ [frequency dist] → Σxᵢ = n × x̄ → n = Σxᵢ/x̄
13.2 Mean (Grouped Data — Direct Method)
x̄ = Σfᵢxᵢ / Σfᵢ = Σfᵢxᵢ / N where xᵢ = class mark = (lower limit + upper limit)/2 fᵢ = frequency of ith class N = Σfᵢ = total frequency
13.3 Assumed Mean (Shortcut) Method
x̄ = A + (Σfᵢdᵢ/N) where A = assumed mean (usually central class mark) dᵢ = xᵢ - A (deviation from assumed mean) N = Σfᵢ
13.4 Step Deviation Method
x̄ = A + [(Σfᵢuᵢ/N) × h] where uᵢ = (xᵢ - A)/h h = class width (size) A = assumed mean → dᵢ = uᵢ × h → xᵢ = A + uᵢh
13.5 Median (Grouped Data)
Median = L + [(N/2 - cf)/f] × h where L = lower limit of median class N = Σfᵢ (total frequency) cf = cumulative frequency of class before median class f = frequency of median class h = class width Steps: 1. Find N/2 2. Find class with cf ≥ N/2 → median class 3. Apply formula Twisted: → L = Median - [(N/2 - cf)/f] × h → cf = N/2 - f(Median - L)/h
13.6 Mode (Grouped Data)
Mode = L + [f₁-f₀ / (2f₁-f₀-f₂)] × h where L = lower limit of modal class f₁ = frequency of modal class (highest frequency) f₀ = frequency of class before modal class f₂ = frequency of class after modal class h = class width Twisted: → L = Mode - [(f₁-f₀)/(2f₁-f₀-f₂)] × h → If f₀ = f₂: Mode = L + h/2 [symmetric case]
13.7 Empirical Relationship
Mode = 3 × Median - 2 × Mean → Mean = (3 × Median - Mode)/2 → Median = (Mode + 2 × Mean)/3 → Mean - Mode = 3(Mean - Median) → Mean - Median = (1/3)(Mean - Mode) [This holds approximately for moderately skewed distributions]
13.8 Ogive and Cumulative Frequency
Less-than ogive: plot (upper limit, cf) More-than ogive: plot (lower limit, N - cf) Median = x-coordinate where two ogives intersect
14
Probability
14.1 Classical (Theoretical) Probability
P(E) = n(E)/n(S) = Number of favorable outcomes / Total outcomes 0 ≤ P(E) ≤ 1 P(certain event) = 1 P(impossible event) = 0
14.2 Complementary Probability
P(Ē) = 1 - P(E) (E-bar = complement of E) P(E) + P(Ē) = 1 → P(E) = 1 - P(Ē) → P(Ē) = 1 - P(E) P(not E) = 1 - P(E) P(at least one) = 1 - P(none)
14.3 Standard Sample Spaces
Coin toss: S = {H, T}, n(S) = 2 Two coins: S = {HH,HT,TH,TT}, n(S) = 4 Three coins: n(S) = 8 n coins: n(S) = 2ⁿ One die: n(S) = 6 Two dice: n(S) = 36 Cards (full deck): n(S) = 52 - Hearts: 13, Diamonds: 13, Clubs: 13, Spades: 13 - Red cards: 26, Black cards: 26 - Face cards (J,Q,K): 12 (3 per suit) - Aces: 4, Kings: 4, Queens: 4, Jacks: 4 - Non-face number cards: 36
14.4 Two Dice Probability Reference
Sum = 2: {(1,1)} → P = 1/36 Sum = 3: {(1,2),(2,1)} → P = 2/36 = 1/18 Sum = 4: 3 ways → P = 3/36 = 1/12 Sum = 5: 4 ways → P = 4/36 = 1/9 Sum = 6: 5 ways → P = 5/36 Sum = 7: 6 ways (MAXIMUM) → P = 6/36 = 1/6 Sum = 8: 5 ways → P = 5/36 Sum = 9: 4 ways → P = 4/36 Sum = 10: 3 ways → P = 3/36 = 1/12 Sum = 11: 2 ways → P = 2/36 = 1/18 Sum = 12: {(6,6)} → P = 1/36 Doublets: (1,1),(2,2),(3,3),(4,4),(5,5),(6,6) → P = 6/36 = 1/6
14.5 Addition Rule
P(A∪B) = P(A) + P(B) - P(A∩B) If A and B are mutually exclusive: P(A∩B) = 0 P(A∪B) = P(A) + P(B) P(A∩B) = P(A) + P(B) - P(A∪B)
14.6 Odds
Odds in favor of E = P(E) : P(Ē) = n(E) : n(Ē) Odds against E = P(Ē) : P(E) = n(Ē) : n(E) If odds in favor = m:n: P(E) = m/(m+n) P(Ē) = n/(m+n)
🎓 Part B
Class 12 Mathematics
B1
Relations and Functions
1.1 Types of Relations
Empty Relation: R = ∅ Universal Relation: R = A × A Reflexive: (a,a) ∈ R for all a ∈ A Symmetric: (a,b) ∈ R → (b,a) ∈ R Transitive: (a,b)∈R and (b,c)∈R → (a,c)∈R Equivalence: Reflexive + Symmetric + Transitive
1.2 Types of Functions
One-one (injective): f(a)=f(b) ⟹ a=b Onto (surjective): Range = Codomain Bijective: One-one + Onto Number of functions from A to B: |B|^|A| = n(B)^n(A) Number of one-one functions: ⁿ⁽ᴮ⁾Pₙ₍ₐ₎ = P(n(B), n(A)) [if n(B)≥n(A)] Number of onto functions (|A|=m, |B|=n): Σ(-1)^k C(n,k)(n-k)^m [inclusion-exclusion]
1.3 Composition of Functions
(g∘f)(x) = g(f(x)) (f∘g)(x) = f(g(x)) (g∘f) ≠ (f∘g) in general [not commutative] (h∘g)∘f = h∘(g∘f) [associative] If f and g both one-one → g∘f one-one If f and g both onto → g∘f onto If g∘f one-one → f is one-one If g∘f onto → g is onto
1.4 Inverse Function
If f: A→B bijective, then f⁻¹: B→A exists f⁻¹(f(x)) = x f(f⁻¹(y)) = y f∘f⁻¹ = f⁻¹∘f = I (identity) To find f⁻¹: let y = f(x), solve for x in terms of y
1.5 Binary Operations
Closure: a*b ∈ A for all a,b ∈ A Commutative: a*b = b*a Associative: (a*b)*c = a*(b*c) Identity element e: a*e = e*a = a Inverse of a: a*a⁻¹ = e (if identity exists) Number of binary operations on set with n elements = n^(n²) Number of commutative binary operations = n^(n(n+1)/2)
B2
Inverse Trigonometric Functions
2.1 Domain and Range
Function Domain Range (Principal) sin⁻¹x [-1, 1] [-π/2, π/2] cos⁻¹x [-1, 1] [0, π] tan⁻¹x (-∞, ∞) = ℝ (-π/2, π/2) cosec⁻¹x (-∞,-1]∪[1,∞) [-π/2,π/2]\{0} sec⁻¹x (-∞,-1]∪[1,∞) [0,π]\{π/2} cot⁻¹x (-∞, ∞) = ℝ (0, π)
2.2 Basic Identities
sin⁻¹x + cos⁻¹x = π/2 (|x| ≤ 1) tan⁻¹x + cot⁻¹x = π/2 (x ∈ ℝ) sec⁻¹x + cosec⁻¹x = π/2 (|x| ≥ 1) → cos⁻¹x = π/2 - sin⁻¹x → sin⁻¹x = π/2 - cos⁻¹x → cot⁻¹x = π/2 - tan⁻¹x → tan⁻¹x = π/2 - cot⁻¹x
2.3 Negative Argument
sin⁻¹(-x) = -sin⁻¹x (odd function) tan⁻¹(-x) = -tan⁻¹x (odd function) cosec⁻¹(-x) = -cosec⁻¹x (odd function) cos⁻¹(-x) = π - cos⁻¹x (not odd!) sec⁻¹(-x) = π - sec⁻¹x cot⁻¹(-x) = π - cot⁻¹x
2.4 Reciprocal Relations
sin⁻¹(1/x) = cosec⁻¹x (x ≥ 1 or x ≤ -1) cos⁻¹(1/x) = sec⁻¹x (x ≥ 1 or x ≤ -1) tan⁻¹(1/x) = cot⁻¹x (x > 0) tan⁻¹(1/x) = cot⁻¹x - π (x < 0) → cosec⁻¹x = sin⁻¹(1/x) → sec⁻¹x = cos⁻¹(1/x) → cot⁻¹x = tan⁻¹(1/x) for x>0, cot⁻¹x = π + tan⁻¹(1/x) for x<0
2.5 Double Angle Formulas
2sin⁻¹x = sin⁻¹(2x√(1-x²)) (|x| ≤ 1/√2) 2cos⁻¹x = cos⁻¹(2x²-1) (0 ≤ x ≤ 1) 2tan⁻¹x = tan⁻¹(2x/(1-x²)) (|x| < 1) 2tan⁻¹x = sin⁻¹(2x/(1+x²)) (|x| ≤ 1) 2tan⁻¹x = cos⁻¹((1-x²)/(1+x²)) (x ≥ 0) 3tan⁻¹x = tan⁻¹(3x-x³)/(1-3x²) (|x|<1/√3)
2.6 Sum and Difference Formulas
sin⁻¹x ± sin⁻¹y = sin⁻¹[x√(1-y²) ± y√(1-x²)] cos⁻¹x ± cos⁻¹y = cos⁻¹[xy ∓ √(1-x²)√(1-y²)] tan⁻¹x + tan⁻¹y = tan⁻¹[(x+y)/(1-xy)] (xy < 1) = π + tan⁻¹[(x+y)/(1-xy)] (xy > 1, x>0, y>0) = -π + tan⁻¹[(x+y)/(1-xy)] (xy > 1, x<0, y<0) tan⁻¹x - tan⁻¹y = tan⁻¹[(x-y)/(1+xy)] (xy > -1) = π + tan⁻¹[(x-y)/(1+xy)] (x>0, xy<-1) = -π + tan⁻¹[(x-y)/(1+xy)] (x<0, xy<-1) Derived: tan⁻¹(1/2) + tan⁻¹(1/3) = π/4 tan⁻¹1 + tan⁻¹2 + tan⁻¹3 = π
2.7 Conversion Formulas
sin⁻¹x = cos⁻¹(√(1-x²)) (x ≥ 0) = tan⁻¹(x/√(1-x²)) (|x|<1) cos⁻¹x = sin⁻¹(√(1-x²)) (x ≥ 0) = tan⁻¹(√(1-x²)/x) tan⁻¹x = sin⁻¹(x/√(1+x²)) = cos⁻¹(1/√(1+x²)) For θ = sin⁻¹x: sinθ=x, cosθ=√(1-x²), tanθ=x/√(1-x²) For θ = cos⁻¹x: cosθ=x, sinθ=√(1-x²), tanθ=√(1-x²)/x For θ = tan⁻¹x: tanθ=x, sinθ=x/√(1+x²), cosθ=1/√(1+x²)
B3
Matrices
3.1 Matrix Notation
A = [aᵢⱼ]ₘₓₙ (m rows, n columns) Order = m × n, Total elements = mn aᵢⱼ = element in ith row, jth column
3.2 Types of Matrices
Row matrix: 1 × n Column matrix: m × 1 Square matrix: m = n Diagonal matrix: aᵢⱼ = 0 if i ≠ j Scalar matrix: Diagonal with all diagonal elements equal Identity matrix: I, diagonal with all 1s Zero matrix: O, all elements 0 Upper triangular: aᵢⱼ = 0 if i > j Lower triangular: aᵢⱼ = 0 if i < j
3.3 Transpose
If A = [aᵢⱼ]ₘₓₙ, then Aᵀ = [aⱼᵢ]ₙₓₘ Properties: (Aᵀ)ᵀ = A (A+B)ᵀ = Aᵀ + Bᵀ (kA)ᵀ = kAᵀ (AB)ᵀ = BᵀAᵀ ← REVERSED ORDER! Symmetric matrix: A = Aᵀ → aᵢⱼ = aⱼᵢ Skew-symmetric: A = -Aᵀ → aᵢⱼ = -aⱼᵢ, diagonal = 0 Any square matrix A: A = ½(A+Aᵀ) + ½(A-Aᵀ) [symmetric + skew-symmetric]
3.4 Matrix Operations
Addition: (A+B)ᵢⱼ = aᵢⱼ + bᵢⱼ [same order] Scalar: (kA)ᵢⱼ = kaᵢⱼ Multiplication: (AB)ᵢⱼ = Σₖ aᵢₖbₖⱼ [A: m×n, B: n×p → AB: m×p] AB ≠ BA in general [not commutative] A(BC) = (AB)C [associative] A(B+C) = AB+AC [distributive] AO = OA = O AI = IA = A
3.5 Elementary Row/Column Operations
Rᵢ ↔ Rⱼ [swap rows i and j] Rᵢ → kRᵢ [multiply row i by k ≠ 0] Rᵢ → Rᵢ + kRⱼ [add k times row j to row i]
3.6 Invertible Matrix
AA⁻¹ = A⁻¹A = I A⁻¹ = adjA / |A| (if |A| ≠ 0) (A⁻¹)⁻¹ = A (AB)⁻¹ = B⁻¹A⁻¹ ← REVERSED! (Aᵀ)⁻¹ = (A⁻¹)ᵀ (kA)⁻¹ = (1/k)A⁻¹ |A⁻¹| = 1/|A|
3.7 2×2 Matrix — Quick Formulas
A = [a b; c d] |A| = ad - bc A⁻¹ = (1/(ad-bc)) × [d -b; -c a] adj A = [d -b; -c a] (transpose of cofactor matrix) For 2×2: adj A is obtained by: swapping diagonal elements negating off-diagonal elements
B4
Determinants
4.1 Determinant of 2×2
|A| = |a b| = ad - bc |c d|
4.2 Determinant of 3×3 (Expansion along R₁)
|a₁ b₁ c₁| |a₂ b₂ c₂| = a₁(b₂c₃-b₃c₂) - b₁(a₂c₃-a₃c₂) + c₁(a₂b₃-a₃b₂) |a₃ b₃ c₃| = a₁M₁₁ - b₁M₁₂ + c₁M₁₃ (Mᵢⱼ = minor of element aᵢⱼ) Cofactor Cᵢⱼ = (-1)^(i+j) Mᵢⱼ Sign pattern for cofactors: + - + - + - + - +
4.3 Properties of Determinants
|Aᵀ| = |A| |kA|ₙₓₙ = kⁿ|A| |AB| = |A||B| |A⁻¹| = 1/|A| |A²| = |A|² |Aⁿ| = |A|ⁿ |adj A| = |A|^(n-1) [for n×n matrix] If any row/column = 0 → |A| = 0 If two rows/columns identical → |A| = 0 If one row is k×another row → |A| = 0 Swapping two rows/columns → |A| changes sign
4.4 Adjoint and Inverse
adj A = transpose of cofactor matrix A(adj A) = (adj A)A = |A| × I A⁻¹ = adj A / |A| (|A| ≠ 0) |adj A| = |A|^(n-1) adj(AB) = (adj B)(adj A) adj(adj A) = |A|^(n-2) × A [n×n] adj(Aᵀ) = (adj A)ᵀ adj(kA) = k^(n-1) adj A
4.5 Cramer's Rule
For AX = B: x = D₁/D, y = D₂/D, z = D₃/D D = |A| (coefficient determinant) D₁ = replace column 1 of A by B D₂ = replace column 2 of A by B D₃ = replace column 3 of A by B If D ≠ 0 → unique solution If D = 0 and D₁ = D₂ = D₃ = 0 → infinitely many / no solution If D = 0 and any Dᵢ ≠ 0 → no solution (inconsistent)
4.6 Area Using Determinants
Area of △ with vertices (x₁,y₁), (x₂,y₂), (x₃,y₃): Area = ½ |x₁ y₁ 1| |x₂ y₂ 1| |x₃ y₃ 1| Collinear if Area = 0: |x₁ y₁ 1| |x₂ y₂ 1| = 0 |x₃ y₃ 1| Equation of line through (x₁,y₁) and (x₂,y₂): |x y 1| |x₁ y₁ 1| = 0 |x₂ y₂ 1| → (y-y₁)(x₂-x₁) = (x-x₁)(y₂-y₁)
B5
Continuity and Differentiability
5.1 Continuity Condition
f is continuous at x=a if: 1. f(a) is defined 2. lim[x→a] f(x) exists 3. lim[x→a] f(x) = f(a) LHL = lim[x→a⁻] f(x) = lim[h→0] f(a-h) RHL = lim[x→a⁺] f(x) = lim[h→0] f(a+h) Continuous ↔ LHL = RHL = f(a)
5.2 Standard Derivatives
d/dx (constant) = 0 d/dx (x) = 1 d/dx (xⁿ) = nxⁿ⁻¹ d/dx (√x) = 1/(2√x) d/dx (1/x) = -1/x² d/dx (1/xⁿ) = -n/x^(n+1) Exponential & Log: d/dx (eˣ) = eˣ d/dx (aˣ) = aˣ ln a d/dx (ln x) = 1/x d/dx (log_a x) = 1/(x ln a) Trigonometric: d/dx (sin x) = cos x d/dx (cos x) = -sin x d/dx (tan x) = sec²x d/dx (cot x) = -cosec²x d/dx (sec x) = sec x tan x d/dx (cosec x) = -cosec x cot x Inverse Trig: d/dx (sin⁻¹x) = 1/√(1-x²) d/dx (cos⁻¹x) = -1/√(1-x²) d/dx (tan⁻¹x) = 1/(1+x²) d/dx (cot⁻¹x) = -1/(1+x²) d/dx (sec⁻¹x) = 1/(|x|√(x²-1)) d/dx (cosec⁻¹x) = -1/(|x|√(x²-1))
5.3 Rules of Differentiation
Sum/Difference: (u ± v)' = u' ± v' Scalar: (cu)' = cu' Product: (uv)' = u'v + uv' ← Product Rule (Leibniz) Quotient: (u/v)' = (u'v - uv')/v² ← Quotient Rule (v≠0) Chain: d/dx[f(g(x))] = f'(g(x))·g'(x) ← Chain Rule Extended Product Rule: (uvw)' = u'vw + uv'w + uvw' Extended Chain Rule: d/dx[f(g(h(x)))] = f'(g(h(x)))·g'(h(x))·h'(x)
5.4 Implicit Differentiation
For F(x,y) = 0: dy/dx = -(∂F/∂x)/(∂F/∂y) [partial derivatives method] Or differentiate both sides w.r.t. x, treating y as function of x Example: x² + y² = r² → 2x + 2y(dy/dx) = 0 → dy/dx = -x/y
5.5 Parametric Differentiation
x = f(t), y = g(t) dy/dx = (dy/dt)/(dx/dt) = g'(t)/f'(t) d²y/dx² = (d/dt[dy/dx]) / (dx/dt)
5.6 Logarithmic Differentiation
For y = [f(x)]^g(x): ln y = g(x) ln[f(x)] (1/y)(dy/dx) = g'(x)ln[f(x)] + g(x)·f'(x)/f(x) dy/dx = y × [g'(x)ln f(x) + g(x)f'(x)/f(x)] For y = (f₁·f₂·...)/(g₁·g₂·...): ln y = ln f₁ + ln f₂ + ... - ln g₁ - ln g₂ - ... (1/y)y' = f₁'/f₁ + f₂'/f₂ + ... - g₁'/g₁ - ...
5.7 Higher Order Derivatives
y = f(x) y' = f'(x) = dy/dx [first derivative] y'' = f''(x) = d²y/dx² [second derivative] y''' = f'''(x) = d³y/dx³ [third derivative] yⁿ = f⁽ⁿ⁾(x) = dⁿy/dxⁿ [nth derivative] Leibniz Formula (nth derivative of product): (uv)ⁿ = Σₖ₌₀ⁿ C(n,k) u⁽ᵏ⁾ v⁽ⁿ⁻ᵏ⁾
5.8 Rolle's Theorem
If f: [a,b]→ℝ is: 1. Continuous on [a,b] 2. Differentiable on (a,b) 3. f(a) = f(b) Then ∃ c ∈ (a,b) such that f'(c) = 0
5.9 Mean Value Theorem (Lagrange's MVT)
If f: [a,b]→ℝ is: 1. Continuous on [a,b] 2. Differentiable on (a,b) Then ∃ c ∈ (a,b) such that: f'(c) = [f(b)-f(a)] / (b-a) → f(b) - f(a) = f'(c)(b-a) → c = value(s) satisfying the above [Geometric meaning: slope of chord = slope of tangent at c]
B6
Application of Derivatives
6.1 Rate of Change
Rate of change of y w.r.t. x = dy/dx Rate of change of y w.r.t. t = dy/dt If y = f(x) and x = g(t): dy/dt = (dy/dx)(dx/dt) Rate of change of area of circle w.r.t. radius: dA/dr = 2πr Rate of change of volume of sphere w.r.t. radius: dV/dr = 4πr² Rate of change of volume of cube w.r.t. side: dV/da = 3a²
6.2 Tangent and Normal
Equation of tangent at (x₁,y₁): y - y₁ = m(x - x₁), where m = (dy/dx) at (x₁,y₁) Equation of normal at (x₁,y₁): y - y₁ = -1/m (x - x₁), where m = (dy/dx) at (x₁,y₁) Slope of tangent: m_t = f'(x₁) Slope of normal: m_n = -1/f'(x₁) m_t × m_n = -1 (tangent ⊥ normal) Length of tangent = y√(1+m²)/m Length of normal = y√(1+m²) Length of subtangent = y/m = y/(dy/dx) Length of subnormal = y × m = y(dy/dx) Tangent parallel to x-axis: dy/dx = 0 Tangent parallel to y-axis: dy/dx → ∞ (dx/dy = 0) Tangent passes through origin: y/x = dy/dx (i.e., y=mx, m=dy/dx)
6.3 Increasing and Decreasing Functions
f is strictly increasing on (a,b) if f'(x) > 0 ∀ x∈(a,b) f is strictly decreasing on (a,b) if f'(x) < 0 ∀ x∈(a,b) f is constant on (a,b) if f'(x) = 0 ∀ x∈(a,b) At a critical point: f'(c) = 0 Monotonically increasing: f(x₁) < f(x₂) whenever x₁ < x₂ Monotonically decreasing: f(x₁) > f(x₂) whenever x₁ < x₂
6.4 Maxima and Minima
First Derivative Test: f'(c) = 0 and f' changes + to - at c → local maximum f' changes - to + at c → local minimum f' doesn't change sign → neither (inflection point) Second Derivative Test: f'(c) = 0 and f''(c) < 0 → local maximum at x=c; f(c) = local max value f''(c) > 0 → local minimum at x=c; f(c) = local min value f''(c) = 0 → test inconclusive (use first derivative test) Global/Absolute maximum/minimum on [a,b]: Compare f(a), f(b), and all f(c) where f'(c)=0
6.5 Optimization Formulas
Rectangle of maximum area for given perimeter P: Square: side = P/4, Area = P²/16 Rectangle of minimum perimeter for given area A: Square: side = √A, Perimeter = 4√A Cylinder of maximum volume: r = h Cone of maximum volume inscribed in sphere of radius R: h = 4R/3, r = 2R√2/3 Rectangle inscribed in circle of radius R: Maximum area square: side = R√2, Area = 2R² Cylinder inscribed in sphere of radius R: Maximum volume: h = 2R/√3, r = R√(2/3) V_max = 4πR³/(3√3) Wire of length L bent to maximize area: If circle: r = L/2π, A = L²/4π If square: side = L/4, A = L²/16 Circle has more area than square for same perimeter Box (open top) from square sheet of side a, corners cut x: V = x(a-2x)² dV/dx = 0 → x = a/6 for max volume V_max = 2a³/27
6.6 Approximations (Linear Approximation)
Δy ≈ dy = f'(x)·Δx [for small Δx] f(x + Δx) ≈ f(x) + f'(x)·Δx Relative error: dy/y Percentage error: (dy/y)×100 If y = xⁿ: Δy/y ≈ n(Δx/x) [percentage error multiplied by n]
B7
Integrals
7.1 Standard Integration Formulas
∫ xⁿ dx = xⁿ⁺¹/(n+1) + C (n ≠ -1) ∫ 1/x dx = ln|x| + C ∫ eˣ dx = eˣ + C ∫ aˣ dx = aˣ/ln a + C ∫ 1 dx = x + C Trigonometric: ∫ sin x dx = -cos x + C ∫ cos x dx = sin x + C ∫ tan x dx = ln|sec x| + C = -ln|cos x| + C ∫ cot x dx = ln|sin x| + C ∫ sec x dx = ln|sec x + tan x| + C ∫ cosec x dx = ln|cosec x - cot x| + C ∫ sec²x dx = tan x + C ∫ cosec²x dx = -cot x + C ∫ sec x tan x dx = sec x + C ∫ cosec x cot x dx = -cosec x + C Special: ∫ 1/√(1-x²) dx = sin⁻¹x + C = -cos⁻¹x + C ∫ -1/√(1-x²) dx = cos⁻¹x + C ∫ 1/(1+x²) dx = tan⁻¹x + C = -cot⁻¹x + C ∫ 1/(x√(x²-1)) dx = sec⁻¹x + C = -cosec⁻¹x + C
7.2 Standard Forms (Key Templates)
∫ 1/(x²+a²) dx = (1/a)tan⁻¹(x/a) + C ∫ 1/(x²-a²) dx = (1/2a)ln|(x-a)/(x+a)| + C (|x|>a) ∫ 1/(a²-x²) dx = (1/2a)ln|(a+x)/(a-x)| + C (|x|<a) ∫ 1/√(x²+a²) dx = ln|x + √(x²+a²)| + C ∫ 1/√(x²-a²) dx = ln|x + √(x²-a²)| + C ∫ 1/√(a²-x²) dx = sin⁻¹(x/a) + C ∫ √(a²-x²) dx = (x/2)√(a²-x²) + (a²/2)sin⁻¹(x/a) + C ∫ √(x²+a²) dx = (x/2)√(x²+a²) + (a²/2)ln|x+√(x²+a²)| + C ∫ √(x²-a²) dx = (x/2)√(x²-a²) - (a²/2)ln|x+√(x²-a²)| + C
7.3 (a) Substitution Method (u-substitution)
∫ f(g(x))·g'(x) dx = ∫ f(u) du [let u = g(x)] Common substitutions: √(a²-x²) → x = a sinθ √(a²+x²) → x = a tanθ √(x²-a²) → x = a secθ (a-x)/(a+x) or similar → x = a cos2θ
7.3 (b) Integration by Parts (IBP)
∫ u dv = uv - ∫ v du or ∫ u·v dx = u(∫v dx) - ∫[u'(∫v dx)] dx ILATE priority rule (choose u in this order): I — Inverse trig (sin⁻¹x, tan⁻¹x...) L — Logarithmic (ln x, log x) A — Algebraic (xⁿ, polynomials) T — Trigonometric (sin x, cos x...) E — Exponential (eˣ, aˣ) Standard IBP results: ∫ xeˣ dx = eˣ(x-1) + C ∫ x²eˣ dx = eˣ(x²-2x+2) + C ∫ xⁿeˣ dx = eˣ[xⁿ - nxⁿ⁻¹ + n(n-1)xⁿ⁻² - ...] + C ∫ x sin x dx = -x cos x + sin x + C ∫ x cos x dx = x sin x + cos x + C ∫ x² sin x dx = -x²cos x + 2x sin x + 2cos x + C ∫ ln x dx = x ln x - x + C ∫ x ln x dx = x²/2 ln x - x²/4 + C ∫ sin⁻¹x dx = x sin⁻¹x + √(1-x²) + C ∫ cos⁻¹x dx = x cos⁻¹x - √(1-x²) + C ∫ tan⁻¹x dx = x tan⁻¹x - (1/2)ln(1+x²) + C Special formula: ∫ eˣ[f(x) + f'(x)] dx = eˣ f(x) + C
7.3 (c) Partial Fractions
Proper fraction: degree(numerator) < degree(denominator) Case 1: Distinct linear factors P(x)/[(ax+b)(cx+d)] = A/(ax+b) + B/(cx+d) Case 2: Repeated linear factors P(x)/(ax+b)² = A/(ax+b) + B/(ax+b)² P(x)/(ax+b)³ = A/(ax+b) + B/(ax+b)² + C/(ax+b)³ Case 3: Irreducible quadratic P(x)/[(ax+b)(x²+bx+c)] = A/(ax+b) + (Bx+C)/(x²+bx+c) Case 4: Improper → divide first If degree(P) ≥ degree(Q): P/Q = quotient + remainder/Q
7.3 (d) Integration of Rational Trig Functions
∫ 1/(a + b sinx) dx: let t = tan(x/2) sinx = 2t/(1+t²), cosx = (1-t²)/(1+t²), dx = 2dt/(1+t²) ∫ 1/(a sinx + b cosx) dx = (1/√(a²+b²)) ln|tan(x/2 + α)| + C where tan α = a/b R sin(x+α) form: a sinx + b cosx = R sin(x+α) R = √(a²+b²), tan α = b/a R cos(x-α) form: a cosx + b sinx = R cos(x-α) R = √(a²+b²), tan α = b/a
7.4 Definite Integral Properties
∫ₐᵇ f(x) dx = F(b) - F(a) [where F'(x)=f(x)] P1: ∫ₐᵇ f(x) dx = -∫ᵦₐ f(x) dx P2: ∫ₐᵃ f(x) dx = 0 P3: ∫ₐᵇ f(x) dx = ∫ₐᶜ f(x) dx + ∫ᶜᵇ f(x) dx P4: ∫ₐᵇ f(x) dx = ∫ₐᵇ f(a+b-x) dx ← KING Property P5: ∫₀ᵃ f(x) dx = ∫₀ᵃ f(a-x) dx ← Special King P6: ∫₀²ᵃ f(x) dx = 2∫₀ᵃ f(x) dx [if f(2a-x) = f(x)] = 0 [if f(2a-x) = -f(x)] P7: ∫₋ₐᵃ f(x) dx = 2∫₀ᵃ f(x) dx [if f even: f(-x)=f(x)] = 0 [if f odd: f(-x)=-f(x)] P8: ∫₀ⁿᵀ f(x) dx = n∫₀ᵀ f(x) dx [if f periodic with period T]
7.5 Definite Integral as Limit of Sum
∫ₐᵇ f(x) dx = lim[n→∞] h Σₖ₌₀ⁿ⁻¹ f(a+kh) where h = (b-a)/n Or: ∫₀¹ f(x) dx = lim[n→∞] (1/n) Σₖ₌₁ⁿ f(k/n)
7.6 Important Definite Integrals
∫₀^(π/2) sin x dx = ∫₀^(π/2) cos x dx = 1 ∫₀^π sin x dx = 2, ∫₀^π cos x dx = 0 ∫₀^(π/2) sin²x dx = ∫₀^(π/2) cos²x dx = π/4 ∫₀^(π/2) sinⁿx dx: n=2: π/4 n=3: 2/3 n=4: 3π/16 ∫₀^(π/2) ln(sinx) dx = ∫₀^(π/2) ln(cosx) dx = -(π/2)ln2 ∫₀^π x f(sinx) dx = (π/2)∫₀^π f(sinx) dx [using King property]
7.7 Walli's Formula
∫₀^(π/2) sinⁿx dx = ∫₀^(π/2) cosⁿx dx = [(n-1)(n-3)...3·1]/[n(n-2)...4·2] × π/2 (n even) [(n-1)(n-3)...4·2]/[n(n-2)...3·1] (n odd)
B8
Application of Integrals
8.1 Area Under a Curve
Area between y=f(x) and x-axis, from x=a to x=b: A = ∫ₐᵇ |f(x)| dx If f(x) ≥ 0: A = ∫ₐᵇ f(x) dx If f(x) ≤ 0: A = -∫ₐᵇ f(x) dx = ∫ₐᵇ |f(x)| dx Area between x=g(y) and y-axis, from y=c to y=d: A = ∫ᶜᵈ |g(y)| dy
8.2 Area Between Two Curves
Area between y=f(x) and y=g(x), a to b [f(x) ≥ g(x)]: A = ∫ₐᵇ [f(x) - g(x)] dx Area between x=f(y) and x=g(y) [f(y) ≥ g(y)]: A = ∫ᶜᵈ [f(y) - g(y)] dy Finding intersection points: solve f(x) = g(x)
8.3 Standard Areas
Circle x²+y²=r²: Area = πr² (full) Area = πr²/2 (semicircle) Ellipse x²/a²+y²/b²=1: Area = πab Area of parabola y=x² and y=x: Intersect at x=0,1 A = ∫₀¹(x-x²)dx = [x²/2 - x³/3]₀¹ = 1/2-1/3 = 1/6 Area of ellipse arc with x-axis: ∫₀ᵃ b√(1-x²/a²)dx = πab/4 [first quadrant]
B9
Differential Equations
9.1 Order, Degree, and Type
Order = highest derivative present Degree = power of highest order derivative (when polynomial in derivatives) Degree undefined if sin(y'), eʸ' etc. Linear DE: highest power of y and its derivatives is 1 Non-linear: otherwise
9.2 Variable Separable Method
dy/dx = f(x)·g(y) → dy/g(y) = f(x)dx → ∫ dy/g(y) = ∫ f(x)dx + C Particular solution: use initial condition to find C
9.3 Homogeneous Differential Equation
dy/dx = f(x,y)/g(x,y) where f,g are homogeneous of same degree Substitution: y = vx → dy/dx = v + x(dv/dx) v + x(dv/dx) = F(v) x(dv/dx) = F(v) - v ∫ dv/[F(v)-v] = ∫ dx/x + C [After integrating, back-substitute v = y/x]
9.4 Linear Differential Equation (First Order)
dy/dx + P(x)y = Q(x) Integrating Factor (IF) = e^(∫P dx) Solution: y × IF = ∫[Q × IF] dx + C → ye^(∫Pdx) = ∫[Q·e^(∫Pdx)] dx + C For dx/dy + P(y)x = Q(y) [x as dependent]: IF = e^(∫P(y)dy) x × IF = ∫[Q(y)·IF] dy + C
9.5 Bernoulli's Equation
dy/dx + P(x)y = Q(x)yⁿ (n ≠ 0, 1) Substitution: z = y^(1-n) dz/dx = (1-n)y^(-n)(dy/dx) Becomes linear: dz/dx + (1-n)P(x)z = (1-n)Q(x)
9.6 General Solutions
∫ dy/y = ln|y| ∫ dy/y² = -1/y ∫ dy/(1+y²) = tan⁻¹y For xdy + ydx = d(xy) [exact differential] For (xdy-ydx)/x² = d(y/x) For (ydx-xdy)/y² = d(x/y) For (xdx+ydy) = (1/2)d(x²+y²)
9.7 Important Differential Equations and Solutions
dy/dx = ky: y = Ce^(kx) [growth/decay] d²y/dx² + n²y = 0: y = A cos(nx) + B sin(nx) d²y/dx² - n²y = 0: y = Ae^(nx) + Be^(-nx) d²y/dx² = f(x): integrate twice Population: dP/dt = kP → P = P₀e^(kt) Radioactive: dN/dt = -λN → N = N₀e^(-λt) Newton's cooling: dT/dt = -k(T-T₀) → T-T₀ = (T₁-T₀)e^(-kt)
B10
Vector Algebra
10.1 Vector Notation
Position vector of A(x,y,z): a⃗ = xî + yĵ + zk̂ Magnitude: |a⃗| = √(x²+y²+z²) Unit vector: â = a⃗/|a⃗| Zero vector: 0⃗ = 0î + 0ĵ + 0k̂ Direction cosines: l = x/|a⃗|, m = y/|a⃗|, n = z/|a⃗| l² + m² + n² = 1 Direction ratios: proportional to (x,y,z)
10.2 Vector Operations
Addition: a⃗ + b⃗ = (a₁+b₁)î + (a₂+b₂)ĵ + (a₃+b₃)k̂ Subtraction: a⃗ - b⃗ = (a₁-b₁)î + (a₂-b₂)ĵ + (a₃-b₃)k̂ Scalar multiple: ka⃗ = ka₁î + ka₂ĵ + ka₃k̂ |a⃗ + b⃗|² = |a⃗|² + 2a⃗·b⃗ + |b⃗|² |a⃗ - b⃗|² = |a⃗|² - 2a⃗·b⃗ + |b⃗|² |a⃗ + b⃗|² + |a⃗ - b⃗|² = 2(|a⃗|² + |b⃗|²) [Parallelogram law] |a⃗ + b⃗|² - |a⃗ - b⃗|² = 4(a⃗·b⃗)
10.3 Dot Product (Scalar Product)
a⃗·b⃗ = |a⃗||b⃗|cosθ = a₁b₁ + a₂b₂ + a₃b₃ → cosθ = a⃗·b⃗ / (|a⃗||b⃗|) → θ = cos⁻¹[a⃗·b⃗ / (|a⃗||b⃗|)] Perpendicular ↔ a⃗·b⃗ = 0 (a⃗ ≠ 0⃗, b⃗ ≠ 0⃗) Parallel ↔ a⃗×b⃗ = 0⃗ î·î = ĵ·ĵ = k̂·k̂ = 1 î·ĵ = ĵ·k̂ = k̂·î = 0 a⃗·a⃗ = |a⃗|² a⃗·b⃗ = b⃗·a⃗ [commutative] Projection of a⃗ on b⃗ = (a⃗·b⃗)/|b⃗| Component of a⃗ along b⃗ = (a⃗·b⃗)/|b⃗| [scalar] Vector projection = [(a⃗·b⃗)/|b⃗|²] b⃗
10.4 Cross Product (Vector Product)
a⃗×b⃗ = |a⃗||b⃗|sinθ n̂ |a⃗×b⃗| = |a⃗||b⃗|sinθ → sinθ = |a⃗×b⃗| / (|a⃗||b⃗|) a⃗×b⃗ = |î ĵ k̂ | |a₁ a₂ a₃| |b₁ b₂ b₃| = î(a₂b₃-a₃b₂) - ĵ(a₁b₃-a₃b₁) + k̂(a₁b₂-a₂b₁) î×î = ĵ×ĵ = k̂×k̂ = 0⃗ î×ĵ = k̂, ĵ×k̂ = î, k̂×î = ĵ [cyclic] ĵ×î = -k̂, k̂×ĵ = -î, î×k̂ = -ĵ [anti-cyclic] a⃗×b⃗ = -(b⃗×a⃗) [anti-commutative] Area of parallelogram = |a⃗×b⃗| Area of triangle = ½|a⃗×b⃗| Area of △ABC = ½|AB⃗×AC⃗|
10.5 Scalar Triple Product
[a⃗ b⃗ c⃗] = a⃗·(b⃗×c⃗) = scalar = |a₁ a₂ a₃| |b₁ b₂ b₃| |c₁ c₂ c₃| Volume of parallelepiped = |[a⃗ b⃗ c⃗]| Volume of tetrahedron = (1/6)|[a⃗ b⃗ c⃗]| Coplanar vectors ↔ [a⃗ b⃗ c⃗] = 0 [a⃗ b⃗ c⃗] = [b⃗ c⃗ a⃗] = [c⃗ a⃗ b⃗] [cyclic] [a⃗ b⃗ c⃗] = -[b⃗ a⃗ c⃗] [swap any two → sign changes]
10.6 Vector Triple Product
a⃗×(b⃗×c⃗) = (a⃗·c⃗)b⃗ - (a⃗·b⃗)c⃗ [BAC-CAB rule] (a⃗×b⃗)×c⃗ = (a⃗·c⃗)b⃗ - (b⃗·c⃗)a⃗
10.7 Section Formula in Vectors
If P divides AB in ratio m:n internally: p⃗ = (mb⃗ + na⃗)/(m+n) Midpoint: p⃗ = (a⃗ + b⃗)/2 Externally: p⃗ = (mb⃗ - na⃗)/(m-n)
B11
Three Dimensional Geometry
11.1 Direction Cosines and Ratios
For line with direction ratios (a,b,c): l = a/√(a²+b²+c²) m = b/√(a²+b²+c²) n = c/√(a²+b²+c²) l²+m²+n² = 1 always cos α = l, cos β = m, cos γ = n (α, β, γ = angles with x,y,z axes) cos²α + cos²β + cos²γ = 1 sin²α + sin²β + sin²γ = 2 [derived]
11.2 Angle Between Two Lines
Lines with DRs (a₁,b₁,c₁) and (a₂,b₂,c₂): cos θ = |a₁a₂+b₁b₂+c₁c₂| / [√(a₁²+b₁²+c₁²)·√(a₂²+b₂²+c₂²)] Parallel: a₁/a₂ = b₁/b₂ = c₁/c₂ Perpendicular: a₁a₂ + b₁b₂ + c₁c₂ = 0 With DCs (l₁,m₁,n₁) and (l₂,m₂,n₂): cos θ = |l₁l₂ + m₁m₂ + n₁n₂|
11.3 Equation of a Line
Vector Form: r⃗ = a⃗ + λb⃗ [passing through point a⃗, direction b⃗] r⃗ = a⃗ + λ(b⃗-a⃗) [passing through a⃗ and b⃗] Cartesian/Symmetric Form: (x-x₁)/a = (y-y₁)/b = (z-z₁)/c = λ x = x₁+aλ, y = y₁+bλ, z = z₁+cλ
11.4 Distance Between Two Lines
Skew lines (r⃗=a⃗₁+λb⃗₁ and r⃗=a⃗₂+μb⃗₂): d = |(a⃗₂-a⃗₁)·(b⃗₁×b⃗₂)| / |b⃗₁×b⃗₂| Parallel lines (b⃗₁ ∥ b⃗₂=b⃗): d = |(a⃗₂-a⃗₁)×b⃗| / |b⃗| Intersecting lines: d = 0 Coplanar lines: (a⃗₂-a⃗₁)·(b⃗₁×b⃗₂) = 0
11.5 Equation of a Plane
Vector Form: r⃗·n̂ = d [n̂ = unit normal, d = distance from origin] r⃗·n⃗ = D [n⃗ = normal vector (not unit)] Cartesian Form: ax + by + cz = d [a,b,c = normal direction] ax + by + cz + d = 0 Normal form: lx + my + nz = p Intercept Form: x/α + y/β + z/γ = 1 [α,β,γ = x,y,z intercepts] Plane through 3 points A(x₁,y₁,z₁), B, C: |x-x₁ y-y₁ z-z₁| |x₂-x₁ y₂-y₁ z₂-z₁| = 0 |x₃-x₁ y₃-y₁ z₃-z₁|
11.6 Angle Between Two Planes
Planes a₁x+b₁y+c₁z+d₁=0 and a₂x+b₂y+c₂z+d₂=0: cos θ = |a₁a₂+b₁b₂+c₁c₂| / [√(a₁²+b₁²+c₁²)·√(a₂²+b₂²+c₂²)] Parallel: a₁/a₂ = b₁/b₂ = c₁/c₂ Perpendicular: a₁a₂ + b₁b₂ + c₁c₂ = 0
11.7 Distance Formulas in 3D
Distance between P(x₁,y₁,z₁) and Q(x₂,y₂,z₂): d = √[(x₂-x₁)²+(y₂-y₁)²+(z₂-z₁)²] Distance from point P(x₁,y₁,z₁) to plane ax+by+cz+d=0: d = |ax₁+by₁+cz₁+d| / √(a²+b²+c²) Distance between parallel planes ax+by+cz=d₁ and ax+by+cz=d₂: d = |d₁-d₂| / √(a²+b²+c²) Foot of perpendicular from P(x₁,y₁,z₁) to plane ax+by+cz+d=0: (x-x₁)/a = (y-y₁)/b = (z-z₁)/c = -(ax₁+by₁+cz₁+d)/(a²+b²+c²)
11.8 Angle Between Line and Plane
Line: r⃗ = a⃗ + λb⃗, Plane: r⃗·n⃗ = d sin φ = |b⃗·n⃗| / (|b⃗||n⃗|) [φ = angle with plane] cos θ = |b⃗·n⃗| / (|b⃗||n⃗|) [θ = angle with normal] Line ∥ plane ↔ b⃗·n⃗ = 0 Line ⊥ plane ↔ b⃗ ∥ n⃗ ↔ b⃗×n⃗ = 0⃗ Line in plane ↔ b⃗·n⃗=0 AND a⃗·n⃗=d
11.9 Family of Planes
Plane through intersection of P₁=0 and P₂=0: P₁ + λP₂ = 0 (for varying λ) (a₁x+b₁y+c₁z+d₁) + λ(a₂x+b₂y+c₂z+d₂) = 0
B12
Linear Programming
12.1 Standard Formulation
Objective Function: Z = ax + by (maximize or minimize) Subject to constraints: a₁x+b₁y ≤/≥/= c₁ etc. Non-negativity: x ≥ 0, y ≥ 0 Feasible Region: set of all points satisfying all constraints Optimal Solution: max/min value of Z at a corner point Corner Point Method: 1. Graph all constraints 2. Find feasible region 3. Find corner points (vertices) 4. Evaluate Z at each corner point 5. Max/min Z is the answer
12.2 Fundamental Theorem
If optimal solution exists → it is at a corner point of feasible region If Z = c (constant) is parallel to a boundary → Z takes same value along that boundary (infinite solutions) Unbounded feasible region → Z may or may not have optimum
12.3 Key Results
For maximize Z = ax+by: → Look for corner with largest x if a>b, etc. For minimize Z = ax+by: → Look for corner nearest to origin (usually) If feasible region is empty → no solution (infeasible problem) If feasible region is bounded → both max and min exist If unbounded → only one of max/min may exist
B13
Probability (Class 12)
13.1 Conditional Probability
P(A|B) = P(A∩B)/P(B) [probability of A given B, P(B)≠0] → P(A∩B) = P(B)·P(A|B) = P(A)·P(B|A) → P(B|A) = P(A∩B)/P(A) → P(A|B) · P(B) = P(B|A) · P(A) Properties: 0 ≤ P(A|B) ≤ 1 P(S|B) = 1 P(A'|B) = 1 - P(A|B) P(A∪C|B) = P(A|B) + P(C|B) - P(A∩C|B)
13.2 Multiplication Theorem
P(A∩B) = P(A)·P(B|A) = P(B)·P(A|B) P(A∩B∩C) = P(A)·P(B|A)·P(C|A∩B) Independent events A and B: P(A|B) = P(A) and P(B|A) = P(B) P(A∩B) = P(A)·P(B) Pairwise independent ≠ mutually independent Mutually independent ↔ every subset satisfies multiplication rule
13.3 Total Probability Theorem
If B₁, B₂, ..., Bₙ are mutually exclusive and exhaustive events: P(A) = Σᵢ P(Bᵢ)·P(A|Bᵢ) = P(B₁)P(A|B₁) + P(B₂)P(A|B₂) + ... + P(Bₙ)P(A|Bₙ)
13.4 Bayes' Theorem
P(Bᵢ|A) = P(Bᵢ)·P(A|Bᵢ) / Σⱼ P(Bⱼ)·P(A|Bⱼ) P(Bᵢ)·P(A|Bᵢ) = ───────────────────────────────────────────── P(B₁)P(A|B₁) + P(B₂)P(A|B₂) + ... + P(Bₙ)P(A|Bₙ) Two hypotheses B₁, B₂ (prior probs p₁, p₂ = 1-p₁): P(B₁|A) = p₁·P(A|B₁) / [p₁·P(A|B₁) + p₂·P(A|B₂)]
13.5 Random Variables and Probability Distribution
If X is a random variable taking values x₁, x₂, ..., xₙ with probabilities p₁, p₂, ..., pₙ: Conditions: pᵢ ≥ 0 for all i, Σpᵢ = 1 Mean (Expected Value): E(X) = μ = Σxᵢpᵢ = x₁p₁ + x₂p₂ + ... + xₙpₙ Variance: Var(X) = σ² = E(X²) - [E(X)]² = Σxᵢ²pᵢ - (Σxᵢpᵢ)² = E[(X-μ)²] = Σ(xᵢ-μ)²pᵢ Standard Deviation: σ = √Var(X) = √[E(X²) - (E(X))²] Properties: E(aX+b) = aE(X) + b Var(aX+b) = a²Var(X) Var(aX) = a²Var(X) Var(X+b) = Var(X)
13.6 Binomial Distribution
X ~ B(n, p) [n = trials, p = success prob, q = 1-p] P(X = r) = C(n,r) · pʳ · qⁿ⁻ʳ (r = 0,1,2,...,n) where C(n,r) = n! / [r!(n-r)!] = ⁿCᵣ Mean: E(X) = np Variance: Var(X) = npq = np(1-p) SD: σ = √(npq) Mode: (n+1)p [if integer, two modes: (n+1)p and (n+1)p-1] ⌊(n+1)p⌋ [if not integer] P(X=0) = qⁿ P(X=n) = pⁿ P(X≥1) = 1 - P(X=0) = 1 - qⁿ Recurrence: P(X=r+1)/P(X=r) = [(n-r)/(r+1)] × (p/q) For large n, small p (np=λ fixed) → Poisson approximation: P(X=r) ≈ e^(-λ)λʳ/r!
13.7 Important Probability Results
P(A only) = P(A∩B') = P(A) - P(A∩B) P(B only) = P(A'∩B) = P(B) - P(A∩B) P(exactly one of A,B) = P(A) + P(B) - 2P(A∩B) P(neither A nor B) = 1 - P(A∪B) = 1 - P(A) - P(B) + P(A∩B) For three events: P(A∪B∪C) = P(A)+P(B)+P(C)-P(A∩B)-P(B∩C)-P(C∩A)+P(A∩B∩C) If A and B independent: A and B' independent A' and B independent A' and B' independent P(A∩B) = P(A)P(B) [independent] P(A∩B) = 0 [mutually exclusive] Independent ≠ mutually exclusive (unless P(A)=0 or P(B)=0)
🔥 Part C
Additional / Advanced Formulas
C1
Advanced Algebra Identities
Algebraic Expansions
(a+b+c)² = a²+b²+c²+2ab+2bc+2ca (a-b-c)² = a²+b²+c²-2ab+2bc-2ca (a+b-c)² = a²+b²+c²+2ab-2bc-2ca a²+b²+c² = (a+b+c)² - 2(ab+bc+ca) ab+bc+ca = [(a+b+c)²-(a²+b²+c²)]/2 (a+b+c)³ = a³+b³+c³+3(a+b)(b+c)(c+a) a³+b³+c³-3abc = (a+b+c)(a²+b²+c²-ab-bc-ca) = ½(a+b+c)[(a-b)²+(b-c)²+(c-a)²] If a+b+c=0: a³+b³+c³ = 3abc (a+b)⁴ = a⁴+4a³b+6a²b²+4ab³+b⁴ (a-b)⁴ = a⁴-4a³b+6a²b²-4ab³+b⁴ a⁴-b⁴ = (a+b)(a-b)(a²+b²) a⁴+b⁴ = (a²+b²)²-2a²b² Binomial: (a+b)ⁿ = Σₖ₌₀ⁿ C(n,k)aⁿ⁻ᵏbᵏ General term: T(r+1) = C(n,r)aⁿ⁻ʳbʳ Middle term: T((n/2)+1) for even n Sophie Germain Identity: a⁴+4b⁴ = (a²+2b²+2ab)(a²+2b²-2ab)
C2
Complete Trigonometry Identities
Compound Angle Formulas
sin(A+B) = sinA cosB + cosA sinB sin(A-B) = sinA cosB - cosA sinB cos(A+B) = cosA cosB - sinA sinB cos(A-B) = cosA cosB + sinA sinB tan(A+B) = (tanA + tanB)/(1 - tanA tanB) tan(A-B) = (tanA - tanB)/(1 + tanA tanB) sin(A+B)·sin(A-B) = sin²A - sin²B = cos²B - cos²A cos(A+B)·cos(A-B) = cos²A - sin²B = cos²B - sin²A
Double Angle Formulas
sin 2A = 2 sinA cosA = 2tanA/(1+tan²A) cos 2A = cos²A - sin²A = 1-2sin²A = 2cos²A-1 = (1-tan²A)/(1+tan²A) tan 2A = 2tanA/(1-tan²A) sin²A = (1-cos2A)/2 cos²A = (1+cos2A)/2 tan²A = (1-cos2A)/(1+cos2A) sin A = 2sin(A/2)cos(A/2) cos A = 1-2sin²(A/2) = 2cos²(A/2)-1
Triple Angle Formulas
sin 3A = 3sinA - 4sin³A cos 3A = 4cos³A - 3cosA tan 3A = (3tanA - tan³A)/(1-3tan²A) sin³A = (3sinA - sin3A)/4 cos³A = (3cosA + cos3A)/4
Product to Sum Formulas
2sinA cosB = sin(A+B) + sin(A-B) 2cosA sinB = sin(A+B) - sin(A-B) 2cosA cosB = cos(A+B) + cos(A-B) 2sinA sinB = cos(A-B) - cos(A+B)
Sum to Product Formulas
sinC + sinD = 2sin((C+D)/2)cos((C-D)/2) sinC - sinD = 2cos((C+D)/2)sin((C-D)/2) cosC + cosD = 2cos((C+D)/2)cos((C-D)/2) cosC - cosD = -2sin((C+D)/2)sin((C-D)/2)
Important Trig Values
sin 15° = (√6-√2)/4 cos 15° = (√6+√2)/4 sin 18° = (√5-1)/4 cos 36° = (√5+1)/4 sin 36° = √(10-2√5)/4 cos 18° = √(10+2√5)/4 sin 22.5° = √((√2-1)/(2√2)) tan 15° = 2-√3 tan 75° = 2+√3
C3
Mensuration Advanced Formulas
Regular polygon (n sides, side a): Perimeter = na Interior angle = (n-2)×180°/n Exterior angle = 360°/n Area = (na²/4)cot(π/n) Sum of interior angles = (n-2)×180° Heron's Formula (triangle with sides a,b,c): s = (a+b+c)/2 [semi-perimeter] Area = √[s(s-a)(s-b)(s-c)] Area using angles (triangle): Area = (1/2)ab sinC = (1/2)bc sinA = (1/2)ca sinB Circumradius R of triangle: R = abc/(4 × Area) = a/(2sinA) Inradius r of triangle: r = Area/s = (s-a)tan(A/2) Cosine Rule: a² = b²+c²-2bc cosA b² = a²+c²-2ac cosB c² = a²+b²-2ab cosC → cosA = (b²+c²-a²)/(2bc) Sine Rule: a/sinA = b/sinB = c/sinC = 2R
C4
Coordinate Geometry Advanced (Class 12 Level)
Standard curves: Circle: x²+y²+2gx+2fy+c=0 Center: (-g,-f), Radius: √(g²+f²-c) Parabola: y²=4ax (opens right, vertex origin) Directrix: x=-a, Focus: (a,0), Axis: y=0 y²=-4ax (opens left) x²=4ay (opens up), x²=-4ay (opens down) Ellipse: x²/a²+y²/b²=1 (a>b>0) c²=a²-b² (c=focal distance) e=c/a<1 (eccentricity) Foci: (±c,0), Vertices: (±a,0) Directrices: x=±a/e=±a²/c Hyperbola: x²/a²-y²/b²=1 b²=c²-a², e=c/a>1 Asymptotes: y=±(b/a)x Conjugate: y²/a²-x²/b²=1 Tangent to circle x²+y²=r² at (x₁,y₁): xx₁+yy₁=r² Tangent to parabola y²=4ax at (x₁,y₁): yy₁=2a(x+x₁) Tangent to ellipse x²/a²+y²/b²=1 at (x₁,y₁): xx₁/a²+yy₁/b²=1 Tangent of slope m to parabola y²=4ax: y=mx+a/m Tangent of slope m to ellipse: y=mx±√(a²m²+b²)
C5
Limits — Key Formulas
Standard Limits: lim[x→0] sinx/x = 1 lim[x→0] tanx/x = 1 lim[x→0] (1-cosx)/x = 0 lim[x→0] (1-cosx)/x² = 1/2 lim[x→0] sin⁻¹x/x = 1 lim[x→0] tan⁻¹x/x = 1 lim[x→0] (eˣ-1)/x = 1 lim[x→0] (aˣ-1)/x = ln a lim[x→0] (ln(1+x))/x = 1 lim[x→∞] (1+1/x)ˣ = e lim[x→0] (1+x)^(1/x) = e lim[x→a] (xⁿ-aⁿ)/(x-a) = naⁿ⁻¹ L'Hôpital's Rule (0/0 or ∞/∞ form): lim f(x)/g(x) = lim f'(x)/g'(x) Special: lim[x→∞] xⁿ/eˣ = 0 (exponential grows faster) lim[x→∞] ln x/xⁿ = 0 (power grows faster than log)
C6
Sequences and Series (Additional)
Geometric Progression (GP)
aₙ = ar^(n-1) [nth term] r = common ratio = aₙ₊₁/aₙ Sum of n terms: Sₙ = a(rⁿ-1)/(r-1) (r ≠ 1, r > 1 preferred) Sₙ = a(1-rⁿ)/(1-r) (r ≠ 1, r < 1 preferred) Sₙ = na (r = 1) Sum to infinity (|r|<1): S∞ = a/(1-r) Product of first n terms of GP: P = aⁿ × r^(n(n-1)/2) GM between a and b: G = √(ab) AM ≥ GM for positive reals: (a+b)/2 ≥ √(ab) HM between a and b: H = 2ab/(a+b) AM ≥ GM ≥ HM GM² = AM × HM 3 terms in GP: a/r, a, ar [product = a³] 4 terms in GP: a/r³, a/r, ar, ar³ [product = a⁴]
Harmonic Progression (HP)
If a,b,c in HP: 1/a, 1/b, 1/c in AP → 2/b = 1/a + 1/c → b = 2ac/(a+c) nth term of HP: 1/(A + (n-1)D)
AGP (Arithmetico-Geometric Progression)
a, (a+d)r, (a+2d)r², ... S∞ = a/(1-r) + dr/(1-r)² [|r|<1]
C7
Combinatorics (for Probability)
Permutation: ⁿPᵣ = n!/(n-r)! [order matters] Combination: ⁿCᵣ = n!/[r!(n-r)!] [order doesn't matter] ⁿCᵣ = ⁿCₙ₋ᵣ ⁿCᵣ + ⁿCᵣ₋₁ = ⁿ⁺¹Cᵣ [Pascal's identity] ⁿCₒ = ⁿCₙ = 1 ⁿC₁ = n ⁿC₂ = n(n-1)/2 ⁿCᵣ = (n/r)ⁿ⁻¹Cᵣ₋₁ n! = n × (n-1)! 0! = 1 Circular permutation: (n-1)! Necklace/bracelet: (n-1)!/2 Multinomial: n!/(n₁!n₂!...nₖ!) Stars and bars: distributing n identical into k distinct: C(n+k-1, k-1)
C8
Complex Numbers
z = a + ib [a = real part, b = imaginary part] i = √(-1), i² = -1, i³ = -i, i⁴ = 1 Modulus: |z| = √(a²+b²) Argument: arg(z) = θ = tan⁻¹(b/a) [in correct quadrant] Conjugate: z̄ = a - ib z + z̄ = 2a = 2Re(z) z - z̄ = 2ib = 2i·Im(z) z·z̄ = |z|² = a²+b² (z̄₁+z₂) = z̄₁+z̄₂ (z₁z₂) = z̄₁·z̄₂ Polar form: z = r(cosθ + i sinθ) = reⁱθ r = |z|, θ = arg(z) De Moivre's theorem: (cosθ+i sinθ)ⁿ = cos(nθ)+i sin(nθ) |z₁z₂| = |z₁||z₂| arg(z₁z₂) = arg(z₁)+arg(z₂) Triangle inequality: |z₁+z₂| ≤ |z₁|+|z₂| |z₁-z₂| ≥ ||z₁|-|z₂|| nth roots of unity: zⁿ = 1 zₖ = cos(2πk/n)+i sin(2πk/n) for k=0,1,...,n-1 Sum of nth roots = 0 Product of nth roots = (-1)^(n-1) Cube roots of unity: 1, ω, ω² ω = (-1+i√3)/2 = e^(2πi/3) 1+ω+ω² = 0 ω³ = 1 ω² = (-1-i√3)/2
C9
Complete Derivative Table (Quick Reference)
f(x) f'(x) ───────────────────────────────────────── c (constant) 0 x 1 xⁿ nxⁿ⁻¹ √x 1/(2√x) 1/x -1/x² 1/xⁿ -n/x^(n+1) eˣ eˣ eᵃˣ aeᵃˣ aˣ aˣ ln a ln x 1/x log_a x 1/(x ln a) sin x cos x cos x -sin x tan x sec²x cot x -cosec²x sec x sec x tan x cosec x -cosec x cot x sin(ax+b) a cos(ax+b) cos(ax+b) -a sin(ax+b) tan(ax+b) a sec²(ax+b) sin⁻¹x 1/√(1-x²) cos⁻¹x -1/√(1-x²) tan⁻¹x 1/(1+x²) cot⁻¹x -1/(1+x²) sec⁻¹x 1/(|x|√(x²-1)) cosec⁻¹x -1/(|x|√(x²-1)) sin⁻¹(x/a) 1/√(a²-x²) cos⁻¹(x/a) -1/√(a²-x²) tan⁻¹(x/a) a/(a²+x²) |x| x/|x| = sgn(x) (x≠0) xˣ xˣ(1+ln x) f(g(x)) f'(g(x))·g'(x)
C10
Complete Integral Table (Quick Reference)
f(x) ∫f(x)dx ──────────────────────────────────────────────────────────── xⁿ (n≠-1) xⁿ⁺¹/(n+1) + C 1/x ln|x| + C eˣ eˣ + C eᵃˣ eᵃˣ/a + C aˣ aˣ/ln a + C sin x -cos x + C cos x sin x + C tan x ln|sec x| + C cot x ln|sin x| + C sec x ln|sec x + tan x| + C cosec x ln|cosec x - cot x| + C sec²x tan x + C cosec²x -cot x + C sec x tan x sec x + C cosec x cot x -cosec x + C 1/√(1-x²) sin⁻¹x + C -1/√(1-x²) cos⁻¹x + C 1/(1+x²) tan⁻¹x + C -1/(1+x²) cot⁻¹x + C 1/(x²+a²) (1/a)tan⁻¹(x/a) + C 1/(x²-a²) (1/2a)ln|(x-a)/(x+a)| + C 1/(a²-x²) (1/2a)ln|(a+x)/(a-x)| + C 1/√(a²-x²) sin⁻¹(x/a) + C 1/√(x²+a²) ln|x+√(x²+a²)| + C 1/√(x²-a²) ln|x+√(x²-a²)| + C √(a²-x²) (x/2)√(a²-x²)+(a²/2)sin⁻¹(x/a)+C √(x²+a²) (x/2)√(x²+a²)+(a²/2)ln|x+√(x²+a²)|+C √(x²-a²) (x/2)√(x²-a²)-(a²/2)ln|x+√(x²-a²)|+C eˣ[f(x)+f'(x)] eˣf(x) + C x eˣ eˣ(x-1) + C x² eˣ eˣ(x²-2x+2) + C ln x x ln x - x + C x ln x (x²/2)ln x - x²/4 + C sin⁻¹x x sin⁻¹x + √(1-x²) + C tan⁻¹x x tan⁻¹x - (1/2)ln(1+x²) + C cos⁻¹x x cos⁻¹x - √(1-x²) + C sin²x x/2 - sin(2x)/4 + C cos²x x/2 + sin(2x)/4 + C tan²x tan x - x + C cot²x -cot x - x + C sin³x -cos x + cos³x/3 + C cos³x sin x - sin³x/3 + C
C11
Matrices — Additional Important Results
Trace(A) = sum of diagonal elements Trace(AB) = Trace(BA) Rank of matrix = number of non-zero rows in row echelon form For A (m×n): rank(A) ≤ min(m,n) A is invertible ↔ rank(A) = n (full rank) A is singular ↔ |A| = 0 ↔ rank(A) < n Cayley-Hamilton Theorem: Every square matrix satisfies its own characteristic equation. For A 2×2 with char. eq λ²-(trA)λ+|A|=0: A² - (trA)A + |A|I = 0 → A⁻¹ = (A - (trA)I) / |A| [for 2×2 non-singular] For 2×2 A = [a b; c d]: Characteristic equation: λ² - (a+d)λ + (ad-bc) = 0 λ₁+λ₂ = a+d = Trace(A) λ₁·λ₂ = ad-bc = |A| Eigenvalues of diagonal matrix = diagonal elements Eigenvalues of triangular matrix = diagonal elements |A| = product of eigenvalues Trace = sum of eigenvalues If A is orthogonal: AAᵀ = AᵀA = I → A⁻¹ = Aᵀ If A is idempotent: A² = A If A is nilpotent: Aⁿ = O for some n If A is involutory: A² = I → A⁻¹ = A
C12
Special Technique Formulas (Exam Tricks)
Rationalization Tricks
1/(a+b√c) = (a-b√c)/(a²-b²c) 1/(√a+√b) = (√a-√b)/(a-b) Nested radicals: √(a+√b) = √((a+√(a²-b))/2) + √((a-√(a²-b))/2)
Telescoping Sums
Σ[f(k)-f(k-1)] = f(n) - f(0) [collapses to endpoints] 1/(k(k+1)) = 1/k - 1/(k+1) 1/(k(k+1)(k+2)) = (1/2)[1/(k(k+1)) - 1/((k+1)(k+2))] Σ 1/(k(k+1)) from k=1 to n = 1 - 1/(n+1) = n/(n+1)
Inequality Formulas
AM-GM: (a+b)/2 ≥ √(ab) [equality when a=b] (a₁+a₂+...+aₙ)/n ≥ (a₁a₂...aₙ)^(1/n) Cauchy-Schwarz: (a₁b₁+a₂b₂+...+aₙbₙ)² ≤ (a₁²+...+aₙ²)(b₁²+...+bₙ²) Triangle inequality: |a+b| ≤ |a| + |b| ||a|-|b|| ≤ |a-b| For positive x: x + 1/x ≥ 2 [min value 2 at x=1] x² + 1/x² ≥ 2
Useful Number Patterns
1+2+3+...+n = n(n+1)/2 1+3+5+...+(2n-1) = n² 2+4+6+...+2n = n(n+1) 1²+2²+...+n² = n(n+1)(2n+1)/6 1³+2³+...+n³ = [n(n+1)/2]² 1×2+2×3+...+n(n+1) = n(n+1)(n+2)/3 1×1!+2×2!+...+n×n! = (n+1)!-1
Important Constants and Values
π ≈ 3.14159265... e ≈ 2.71828182... √2 ≈ 1.41421356... √3 ≈ 1.73205080... √5 ≈ 2.23606797... 1/√2 = √2/2 ≈ 0.7071 √3/2 ≈ 0.8660 ln 2 ≈ 0.6931 ln 10 ≈ 2.3026 log₁₀ e ≈ 0.4343 Radian to degree: 1 rad = 180°/π ≈ 57.296° Degree to radian: 1° = π/180 rad ≈ 0.01745 rad 30° = π/6 rad 45° = π/4 rad 60° = π/3 rad 90° = π/2 rad 120° = 2π/3 rad 135° = 3π/4 rad 150° = 5π/6 rad 180° = π rad 270° = 3π/2 rad 360° = 2π rad
Differential Calculus — Twisted Forms
If y = sin(ax+b): y' = a cos(ax+b), y'' = -a² sin(ax+b), yⁿ = aⁿ sin(ax+b+nπ/2) If y = cos(ax+b): yⁿ = aⁿ cos(ax+b+nπ/2) If y = eᵃˣ: yⁿ = aⁿeᵃˣ If y = ln x: y' = 1/x, y'' = -1/x², yⁿ = (-1)^(n-1)(n-1)!/xⁿ Partial derivatives (for Lagrange multipliers): ∂/∂x[f(x,y)] — treat y as constant Jacobian: J = ∂(u,v)/∂(x,y) = |∂u/∂x ∂u/∂y| |∂v/∂x ∂v/∂y| Euler's theorem for homogeneous f of degree n: x(∂f/∂x) + y(∂f/∂y) = nf Total differential: df = (∂f/∂x)dx + (∂f/∂y)dy
3D Geometry — Extra Formulas
Sphere with center (h,k,l) and radius r: (x-h)²+(y-k)²+(z-l)² = r² General sphere: x²+y²+z²+2ux+2vy+2wz+d=0 Center: (-u,-v,-w), Radius: √(u²+v²+w²-d) Image of point P(α,β,γ) in plane ax+by+cz+d=0: (x-α)/a = (y-β)/b = (z-γ)/c = -2(aα+bβ+cγ+d)/(a²+b²+c²) Centroid of tetrahedron (4 vertices): G = [(x₁+x₂+x₃+x₄)/4, (y₁+y₂+y₃+y₄)/4, (z₁+z₂+z₃+z₄)/4] Volume of tetrahedron with one vertex at origin, others A,B,C: V = (1/6)|[a⃗ b⃗ c⃗]| Distance from line to line (skew): d = |[(b⃗₁×b⃗₂)·(a⃗₂-a⃗₁)]| / |b⃗₁×b⃗₂|
Vector — Additional Identities
|a⃗×b⃗|² = |a⃗|²|b⃗|² - (a⃗·b⃗)² [Lagrange's identity] (a⃗×b⃗)·(c⃗×d⃗) = (a⃗·c⃗)(b⃗·d⃗) - (a⃗·d⃗)(b⃗·c⃗) (a⃗×b⃗)×(c⃗×d⃗) = [a⃗ b⃗ d⃗]c⃗ - [a⃗ b⃗ c⃗]d⃗ = [a⃗ c⃗ d⃗]b⃗ - [b⃗ c⃗ d⃗]a⃗ Area of parallelogram with diagonals d⃗₁, d⃗₂: Area = ½|d⃗₁×d⃗₂| Normal to plane through a⃗, b⃗, c⃗: n⃗ = (b⃗-a⃗)×(c⃗-a⃗) Angle bisector of a⃗ and b⃗ (unit vectors â,b̂): bisector direction = â + b̂ [internal] = â - b̂ [external]
Exam Strategy — Key Identity Shortcuts
a² + b² + c² - ab - bc - ca = ½[(a-b)² + (b-c)² + (c-a)²] ≥ 0 always (a+b+c)² = a²+b²+c² + 2(ab+bc+ca) If a+b+c=0: a²+b²+c² = -2(ab+bc+ca) ab+bc+ca = -(a²+b²+c²)/2 a³+b³+c³ = 3abc Determinant tricks: R₁→R₁+R₂+R₃ (sum of rows): factor out the sum C₁→C₁-C₂, C₂→C₂-C₃: create zeros If rows in AP: middle row = average of outer rows → use R₂→2R₂-R₁-R₃ Common factor: |ka kb kc| = k × |a b c| |d e f | |d e f| |g h i | |g h i|
CBSE Board Frequent Formula Combos
Volume related conversion: If a sphere of radius R is melted into n small spheres of radius r: (4/3)πR³ = n × (4/3)πr³ → n = R³/r³ = (R/r)³ Cone from circle (sector folded): If a sector of radius L and angle θ is folded into a cone: Slant height of cone = L (radius of sector) 2πr = (θ/360°) × 2πL → r = θL/360° → h = √(L²-r²) → V = (1/3)πr²h Ratio of volumes of cone:cylinder:sphere (same r, same h=2r): V_cone : V_cyl : V_sph = 1 : 3 : 2 [FAMOUS RATIO] Sphere inscribed in cylinder: r_sphere = r_cyl = h_cyl/2 SA_sphere/CSA_cyl = 1 [Equal surface areas!] Largest cone inscribed in cylinder: same base and height V_cone = (1/3)V_cyl Largest sphere inscribed in cube of side a: r = a/2 Largest sphere inscribed in cone of radius R, height h: r = Rh/(√(R²+h²)+R) = Rh/(l+R)
C13
Final Master Summary — The Golden Rules
1. a² - b² = (a+b)(a-b) — always factorize first! 2. D = b²-4ac — discriminant rules everything 3. sin²+cos²=1 — most common identity 4. AM≥GM≥HM — inequalities 5. P(A)+P(Ā)=1 — complement rule 6. aₙ=a+(n-1)d, Sₙ=n/2[2a+(n-1)d] — AP core 7. LCM×HCF = a×b — always 8. Area = ½|base×height| — universally 9. Chain rule: d/dx[f(g(x))]=f'(g(x))g'(x) 10. ∫eˣ[f+f']=eˣf+C — IBP shortcut Key Values to Remember: sin30=1/2, cos60=1/2, tan45=1, sin90=1, cos0=1 √2≈1.414, √3≈1.732, π≈3.14159, e≈2.71828 Key Theorems: - Pythagoras: H²=B²+P² - Thales (BPT): AD/DB=AE/EC - MVT: f'(c)=(f(b)-f(a))/(b-a) - Bayes: P(H|E)=P(H)P(E|H)/P(E) - Euclid: a=bq+r - FTA: Every composite number has unique prime factorization