CBSE Class 9 Maths Formulas

Geometrical Shapes

Area (A)

Perimeter

Rectangle

A = Length x Width

P =  2(Length + Width)

Triangle

A = ½ x Breadth x Height

P = Sum of all the three sides of a triangle

Trapezoid

A = ½ x Height x (b₁ x b₂)

P = Sum of all the sides of a trapezoid

Parallelogram,

A = Breadth x Height

P = 2( a+ b)

Here. a = side

B = base

Circle

A = πr²

P = 2 πr

• (x + β)² = x²  +  β²  +  2 x β

• (x - β)² = x²  +  β²  - 2 x β

• (x + θ) (x - θ) =  x² - θ² 

• (x + α)(x + θ) =  x²  +   (α + θ)x  +  αθ

• (x +  α)(x - θ) =  x²  +  (α - θ)x   -  αθ

• (x - α)(x + θ) =  x²  +  (θ - α)x  -  xθ

• (x - α)(x - θ) = x²  -  (α + θ)x   + αq

• (α + θ)³  = α³ + θ³  +  3αθ(α + θ)

• (α - θ)³ =  α³  + θ³ - 3αθ(α - θ)

• (α + β + θ)²  = α² + β² + θ² + 2αβ + 2βθ + 2αθ

• (α + β - θ)²  = α² + β² + θ² + 2αβ - 2βθ - 2αθ

• (α - β + θ)²  = α² + β² + θ²- 2αβ - 2βθ + 2αθ

• (α - β - θ)²  = α² + β² + θ² - 2αβ + 2βθ - 2αθ

• (x)³ + (β)³ = ( x + β) (x² - xβ + β)

• (x)³ - (β)³ = ( x + β) (x² - xβ + β)

Shape

Surface Area (A)

Volume (V)

Cuboid

2 = (lb + bh + hl), 

Here, l = length, 

b = Breadth, h = height

V = Length x  Breadth x Height

Cube

A = 6 side²

V = Side³

Cylinder

A = 2πr( h + r)

Here,

r = radius of circular cylinder

H = height of a cylinder

V = πr²H

Cone

A = πr( L + r)

Here, 

l = slant height 

r = Radius of base

Also, l² = h² + r², where h is the cone's height 

V = ½ πr²

Sphere

A = 4πr²

V = 4/3πr³

Area of Triangle with 3 sides

√s(s-a)(s-b)(s-c)

Here, s = semi perimeter

A,b, c are the sides of triangle

Semi Perimeter

S = ( a + b + c)/2

P (x) = anxn + an- 1xn- 1 - an- 2xn- 1 + …… ax + a0

Mean 

Sum of all the observations/ Total Number of Observations

Median

For odd observations = ((n+1)/2)th observations

Here, n is he total number of observations

For even Observations - ((n/2)th + ((n/2) +1)th)/2 observations

Mode

Value which occur most frequently in a adata 

Empirical Probability = Number of Trails With Expected Outcomes/ Total Number of Trials