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🎯 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