The perimeter, P, is the distance around a closed plane figure.

Perimeter can be measured in millimetres (mm), centimetres (cm), metres
(m) and kilometres (km). These units are related as follows:

Perimeters of the following figures are often required to solve real
world problems.

Perimeter of a Square

The perimeter, P, of a square is given by the formula

P = 4s

where s is the length of any side of the square.

Note:

The rule (or equation)

P = 4s

represents the relationship between the length of a side of a square and
the perimeter. Such an equation, which gives a rule for working out
the value of one quantity from the values of others, is called a formula.

Example 9

Find the perimeter of a square paddock of side 25 m.