Key Points - Mensuration

- Perimeter: Length of boundary of a simple closed figure.
- Area: The measure of region enclosed in a simple closed figure.
- Area of a trapezium = half of the sum of the lengths of parallel sides × perpendicular distance between them.
- Area of a rhombus = half the product of its diagonals.

- Perimeter of:
Rectangle = 2(l + b)
Square = 4a
Triangle = 1/ 2 × base × height
Parallelogram = 2(sum of two adjacent sides)

- Diagonal of:
Rectangle = sqrt (l^2 + b^2)
Square =sqrt (2a)

- Surface area of a solid is the sum of the areas of its faces.
- Surface area of:

a cuboid = 2 ( lb + bh + hl )

a cube = 6l^2
a cylinder = 2ℼr ( r + h )
  
- Amount of region occupied by a solid is called its volume.

- Volume of
 a cuboid = l × b × h a cube = l 3
 a cylinder = ℼr 2 h

1 cm^3 =  1L
1 L = = 1000 cm^3
 1 m^3 = 1000000 cm^3 = 1000 L