25 Sep

Calculate the Perimeter of a Compound Shape

Perimeter of a Compound Shape

Have you ever needed to learn how to calculate the perimeter of a compound shape?

Let Key Stage 2 Maths help you with our online video tutorial explaining how to calculate perimeter and how you can use it specifically when calculating the perimeter of a compound shape.

Solve common compound shape perimeter calculation problems today!

Compound Shape

A compound shape is the result of two or more simple shapes placed beside each other. An easy to understand example is two rectangles placed together to form an “L” shape.

Perimeter of a compound shape

There will always be instances within Key Stage 2 Maths where you need to work out the perimeter of a compound shape.

We’re now going to calculate the perimeter of a compound shape where some lengths have been provided and some are yet to be determined. Our example compound shape is made up of more than one rectangle.

Example Compound Shape

Here, we have an example compound shape.

Perimeter of a Compound Shape Example

The first thing that you need to do is to split the compound shape into rectangles. This will help you visualise the parallel lines required to help identify the missing lengths.

The first length we need to find is top to bottom.

We need to look for clues to what that length could be. We know that it is parallel to the 3cm line and the 5cm line. If you put them together they would be exactly the same length as the missing length. So, we need to make an addition ..

3cm + 5cm = 8cm

The missing length is therefore 8cm.

Now to find the other missing length. You need to look at what you already know. The lines parallel to it measure 10cm and 4cm. Because we have some of the length then we need to do a subtraction ..

10cm – 4cm = 6cm

Perimeter of a Compound Shape Example

To find the total perimeter we need to make some additions ..

4cm + 3cm + 6cm + 5cm + 10cm + 8cm

Answer: 36cm

Our 3 minute video will cover all that you need to know to calculate the perimeter of a compound shape from a Key Stage 2 Maths perspective.

About the author

Tina Mavadia Primary school teacher who has worked throughout London and Hertfordshire. Add Tina Mavadia to Google Plus or check out my Key Stage 2 Maths channel on YouTube.

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