Perimeter of rectilinear shapes

In a nutshell

The perimeter of a rectilinear figure is the full distance measured around a square or rectangle and can be calculated by adding all the side lengths together. You may have to measure the side lengths, the lengths may be stated or shown on a centimeter square grid.

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How to work out the perimeter of a square

Procedure

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Example 1 

Find the perimeter of the square.

The square is given on a centimetre grid. Count the squares to find the side length. There are four squares, so the length of each side is $$4cm$$. The perimeter can be calculated by multiplying the side length by four.

$$Perimeter = 4 \times 4 = \underline{16cm}$$​​

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How to work out the perimeter of a rectangle

PROCEDURE

Example 2

Find the perimeter of the rectangle.

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The rectangle is given on centimetre square grid, so count squares to find the length and width.

$$Length = 5cm, \space width = 3cm$$​​

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Calculate the perimeter

$$Perimeter = 5+5+3+3=\underline{16cm}$$​​

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Example 3

Find the perimeter of the rectangle.

	​$$7cm$$​​
​$$4cm$$​​

The lengths are already given, so find the perimeter by adding the side lengths up.

$$Perimeter = 7+7+4+4=\underline{22cm}$$​​

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