In this activity, we will be working out the perimeter of a regular 2D polygon.

The perimeter is the total distance around the outside of a 2D shape. We can calculate the perimeter by adding together the length of all the sides.

Remember that in a regular polygon, all the sides are the same length.

Example

Calculate the perimeter of the shape.

3 cm

Answer

First, count the number of sides.

There are 5 sides in this shape. It is a pentagon.

It is regular so each side is 3 cm long.

The perimeter is 5 x 3 = 15 cm

Remember the answer is 15 cm not just 15!

Let's try some questions now!