Perimeter of composite rectilinear shapes

In a nutshell

A composite rectilinear shape is a shape that is made of squares and rectangles put together. The perimeter of a composite shape can be found by adding up all the lengths of the sides of the shape. In order to find the side lengths of the composite shape, you may have to consider the size and side lengths of the individual squares or rectangles that make up the composite shape.

Calculating the perimeter for composite rectilinear shapes

procedure

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Example 1

Find the perimeter of the shape.

The shape is made up of a square and a rectangle joined together. The square has side length $$3cm$$, and the rectangle has length $$3cm$$ and width $$2cm$$. Use these lengths to label the diagram with the side lengths of the composite shape.

Find the perimeter by adding up all the side lengths.

$$Perimeter = 3 +3+3+2+2+3+2+2=\underline{20cm}$$​​