Perimeter
The perimeter is the total distance around the outside of a flat shape. Imagine walking all the way around the edge and back to where you started. To find it, just add the length of every side. For a rectangle, the two long sides are equal and the two short sides are equal, so we can double the length and the width.
Key idea / Formula
Rectangle perimeter = 2 × (length + width). Square perimeter = 4 × side. Area of rectangle = length × width. Area of square = side × side.
Area
The area is the amount of flat space a shape covers. We count it in square units such as cm² or m². For a rectangle, multiply the length by the width.
Worked example
A rectangle is 8 cm long and 5 cm wide.
Perimeter = 2 × (8 + 5) = 2 × 13 = 26 cm.
Area = 8 × 5 = 40 cm².
Remember
- Perimeter is a length, so its unit is cm or m.
- Area is a surface, so its unit is cm² or m².
- All four sides of a square are equal.