Perimeter & Area

The perimeter is the total distance around a shape — the sum of all its sides. For a square, perimeter = 4 × side. For a rectangle, perimeter = 2 × (length + breadth).

So a square of side 5 cm has perimeter 4 × 5 = 20 cm, and a rectangle 6 cm × 4 cm has perimeter 2 × (6 + 4) = 20 cm.

The area is the space inside a shape, measured in square units (sq cm). One way is to count the unit squares that fit inside.

Faster, we use formulas: area of a rectangle = length × breadth, and area of a square = side × side. So a 5 cm × 3 cm rectangle has area 15 sq cm.

Real problems tell us whether to use perimeter or area. Fencing a garden uses the perimeter (the distance around). Carpeting or tiling a floor uses the area (the space inside).