Perimeter of a trapezoid, step by step
A trapezoid's four sides can all be different, so its perimeter is a plain four-number addition with no shortcut.
The question
cm
Perimeter of a 5-5-6-5 trapezoid
sides:5565
sides:5565
sides:5565
5 + 5 + 6 + 5=21 cm
- Perimeter is the distance round the OUTSIDE — the length of the fence, not the size of the field. That is the whole difference between this and area, and it is where the usual wrong answer comes from.
- So there is nothing to work out — just walk round the edge and add: 5 + 5 + 6 + 5.
- 5 + 5 + 6 + 5 = 21 cm. Note the unit: cm, not square cm — a fence is a length, and a length never gets squared.
How it works.
- 01
Perimeter is the distance round the OUTSIDE — the length of the fence, not the size of the field. That is the whole difference between this and area, and it is where the usual wrong answer comes from.
- 02
So there is nothing to work out — just walk round the edge and add: 5 + 5 + 6 + 5.
- 03
5 + 5 + 6 + 5 = 21 cm. Note the unit: cm, not square cm — a fence is a length, and a length never gets squared.