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.
Try it yourself
What is the perimeter of this shape? Count the sides of the squares along the edge.
What is the perimeter of this rectangle? Count the sides of the squares along the edge.
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.