Formulae | Maths Formulas | Important Maths Formulas

Video lectures 

Total Surface & Lateral Surface Area of Cuboid (Video lecture )

Curved & total surface area of a right circular cylinder (Video lecture )

Formulae (Mathematics - Basic)

Area and perimeter of a rectangle 

Perimeter of rectangle = 2(l+b)

Area of a rectangle = l×b

Diagonal of a rectangle = `\sqrt{l^2+b^2}`

Area and perimeter of a square 

Perimeter of a square = 4a

Area of a square = `(side)^2` or,`1/2×(diagonal)^2`

Diagonal of a square = `\sqrt{2}a`

Area and perimeter (circumference) of a circle

Circumference of a circle = 2𝜋r

Area of a circle = 𝜋`r^2`

Area of a triangle

Area of a triangle = `1/2× base × height`

Area of a right angle triangle = `1/2×`product of its legs

Area of an equilateral triangle = `\sqrt3/4a^2`

Area of an isosceles triangle = `1/2 × b× \sqrt{a^2  -  b^2/4}`

If a, b, c are the sides of a `\triangleABC` and s = `1/2(a+b+c)`, then

 area of `\triangleABC = \sqrt{s(s-a)(s-b)(s-c)}`      (Heron's formula)

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Area of a parallelogram = base `×` height

Area of a rhombus = `1/2×` product of diagonals

Area of a trapezium = `1/2 ×` sum of parallel sides `×` distance between them 

or, `1/2 (a+b)×h`

Volume and surface area of solids

Cuboid

Volume of a cuboid =  `l × b × h` 

Diagonal of a cuboid  = `\sqrt {l^2 + b^2 + h^2}`

Total surface area of a cubod = `2(lb+bh+lh)`

Lateral surface area of a cuboid  = `2(l+b)×h`

Cube 

Volume of a cube = `a^3`

Diagonal of a cube = `\sqrt3a`

Total surface of a cube = `6a^2`

Lateral surface area of a cube = `4a^2`

Cylinder 

Volume of a cylinder = 𝜋`r^2`h

Curved (lateral) surface area of a cylinder = 2𝜋rh

Total surface area of a cylinder = 2𝜋r(h+r)

Right circular cone 

Slant height  `l` = `\sqrt{\h^2 + r^2}`

Volume of the cone = `1/3`𝜋`r^2h`

Curved surface area of a cone = 𝜋`rl`

Total surface of a cone = 𝜋`rl` +𝜋`r^2` = 𝜋`r(l+r)`

Work in progress ......