measurement · Year 5 · AC9M5M02
Perimeter of composite shapes
The perimeter is the total distance around the outside of a shape. For a shape with right-angled corners, first make sure you know every side. A missing side can be worked out from the others: opposite directions must balance, so the short sides across the top add up to the long side across the bottom. Then start at one corner and add every side as you go round, ticking each one off. Don't multiply: that gives the area.
Sample questions
What is the perimeter of this shape, in metres? All the corners are right angles.
- Start at one corner and add every side as you go round.
- 8 + 6 + 3 + 2 + 11 + 8 = 38
- The perimeter is 38 m.
Answer: 38
What is the perimeter of this shape, in metres? All the corners are right angles.
- Start at one corner and add every side as you go round.
- 13 + 8 + 3 + 2 + 10 + 10 = 46
- The perimeter is 46 m.
Answer: 46
What is the perimeter of this shape, in metres? All the corners are right angles.
- Start at one corner and add every side as you go round.
- 5 + 3 + 5 + 5 + 10 + 8 = 36
- The perimeter is 36 m.
Answer: 36