Perimeter of a rectangle
You learn to find the perimeter: how far it is all the way round.
How to work it out
- Add all four sides: length + width + length + width.
- Or do (length + width) × 2.
A worked example
A rectangle is 3 m long and 2 m wide. What is the perimeter?
- Add all four sides: 3 + 2 + 3 + 2 = 10.
- The perimeter is 10 m.
More examples
A square has sides of 4 cm. What is the perimeter?
- A square has four equal sides.
- Add them: 4 + 4 + 4 + 4 = 16.
- The perimeter is 16 cm.
A triangle has sides of 5, 6 and 7 cm. What is the perimeter?
- Add all three sides: 5 + 6 + 7 = 18.
- The perimeter is 18 cm.
Watch out
You only add the length and width: 3 + 2 = 5.
The perimeter is the distance all the way round. A rectangle has four sides, so add all four.
Tips
- For a rectangle with length L and width W, the perimeter is L + W + L + W = 2L + 2W.
- For a square with side S, the perimeter is S + S + S + S = 4S.
Why it works
The perimeter is the distance all the way round a shape. If you walk around a rectangle and measure all four sides, the total is the perimeter. You add them up: length + length + width + width.