1.3 Calculate perimeter and area of compound shapes

• Mathematics
• Lower Secondary (Key Stage 3)

Calculate perimeter and area of compound shapes

The perimeter of a shape is?

1. A point on a polygon where the sides or edges of the object meet
2. The total space taken up by a flat (2-D) surface or shape of an object.
3. Is the distance around the edge of a shape.
4. Segments that join one vertex to another and are also where the shape's faces meet.

The area of a shape is?

1. A point on a polygon where the sides or edges of the object meet
2. The total space taken up by a flat (2-D) surface or shape of an object.
3. Is the distance around the edge of a shape
4. Segments that join one vertex to another and are also where the shape's faces meet.

What is a compound shape?

Compound shapes

A composite shape can be defined as a shape created with two or more basic shapes. We often refer to composite shapes as compound and complex shapes as well.

Activity

What two shapes can this compound shape be 'broken' into?

Draw this on your table with a whiteboard marker (include the measurements!)

Photograph your mathematical drawing and post it here!

Activity

What three shapes can this compound shape be 'broken' into?

Draw this on your table with a whiteboard marker (include the measurements!)

Photograph your mathematical drawing and post it here!

Challenge

1. Using ... create two compound shapes and leave them on your table
   
2. Work out the perimeter and area of your shape and write this on a piece of paper (keep the answers in your pocket!)
3. Add some of the perimeter measurements to your shape
4. You have 5 minutes to move around the class and work out the perimeter and area of other shapes - writing your answer and initials on the table with a whiteboard marker
5. Come back and mark the answers that have been written by your shapes

Perimeter and area of compound shapes

Activity

1. In pairs find the perimeter of three of these compound shapes
   
2. In pairs find the perimeter of six of these shapes
3. On your own find the perimeter of all of these shapes

Area of compound shapes

Activity

Area of compound shapes

https://www.khanacademy.org/math/geometry-home/geometry-area-perimeter/geometry-area-trap-composite/e/area-of-quadrilaterals-and-polygons

Area Challenge

https://www.khanacademy.org/math/geometry-home/geometry-area-perimeter/geometry-area-trap-composite/e/composing-and-decomposing-shapes

Find the perimeter of this shape

Find the area of this shape

Find the perimeter of this shape

Activity answers

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