# Finding the perimeter of a rectilinear shape

## Learning focus

Learn how to find the perimeter of a rectilinear shape.

This includes:

- a quiz
- a learning summary
- one video
- one activity

# Quiz

To get started, let's see how well you know this topic already. Take the quiz below to find out.

# Learn

A **rectilinear shape** is a shape that has straight sides and right angles. It can look like two rectangles that have been joined together.

This shape looks much more complicated than a rectangle, but the method of working out the perimeter is exactly the same.

Add together the lengths of all the sides to find it.

2 + 2 + 3 + 3 + 5 + 5 = 20

The perimeter is *20 cm*

### Finding the unknown sides

Watch the video below from BBC Bitesize on finding the perimeter of a rectilinear shape when you don't know the length of every side.

## Example 1

**Can you find the perimeter of this shape?**

## Example 2

**Work out the missing lengths of this shape to find the perimeter.**

# Practise

## Activity

**Make a shape**

Cut out 12 squares of paper of equal size or use 12 square sticky notes (you may have these from yesterday's activity). Arrange them into a rectilinear shape.

What is the perimeter of this shape?

Now rearrange the pieces of paper into a new shape. How many different shapes can you make and find the perimeter of?

# Play

Play **Guardians: Defenders of Mathematica** to learn more and sharpen your skills on this topic.