Calculate the Perimeter of Composite Shapes

In this activity, we're going to be calculating the perimeter of some composite rectangles.

The words in blue may be new to us. 

Let's have a look at them to see what they mean.

 

Perimeter is the distance around the outside of a shape.

 

 

This square has four equal sides of 10 cm

The perimeter of this square is 40 cm (4 x 10 = 40)

 

A composite/compound rectangle is any shape that is made up of two or more rectangles (including squares)

The shape below is made up of two rectangles.  It is a composite rectangle.

 

 

To calculate the perimeter of a composite rectangle, we must add together all of the measurements around the outside of the shape (the perimeter)

Let's have a go:   5 + 4 + 2 + 3 + 3 + 1 = 18  (there are six sides to the shape, so we will have six measures to add)

The unit of measure is metres; we must include this in our answer.

 

The perimeter is 18 m.

 

Sometimes, we have to work out some of the measurements ourselves. 

In this set of questions, we are given all of the measurements!

 

Top Tips:

Check the unit of measure and remember to include it in your answer.

Check the number of sides each shape has and make sure you have included them all.

 

 

Good luck!