Formulas worth knowing
- Rectangle: area = length × breadth; perimeter = 2 × (length + breadth)
- Triangle: area = ½ × base × height
- Circle: area = πr², circumference = 2πr (use 22/7 when the radius is a multiple of 7)
- Cuboid: volume = length × breadth × height
Worked examples
Example 1. A rectangle 24 m by 15 m has area 360 sq m and perimeter 78 m.
Example 2. A circle of radius 7 cm has area (22/7) × 7 × 7 = 154 sq cm.
Unit discipline
Convert all dimensions to the same unit before you begin. Remember that area units are squared and volume units cubed.
See also squares and cubes for faster calculation and SSC CGL quant for exam context.
