# Perimeter

Perimeter is a measurement of the distance around the edge of a two-dimensional shape. Perimeter is an important concept in geometry and is used to calculate the length of the boundary of a shape.

Definition of Perimeter Perimeter is the distance around the edge of a two-dimensional shape. It is the total length of all sides of a polygon or other closed figure. The perimeter is measured in units such as inches, centimeters, or meters.

Calculating Perimeter To calculate the perimeter of a shape, you need to add up the lengths of all its sides.

## The formula for the perimeter of a polygon is:

Perimeter = sum of the lengths of all sides

For example, let’s calculate the perimeter of a rectangle with a length of 6 cm and a width of 4 cm:

Perimeter = 2(length + width) Perimeter = 2(6 cm + 4 cm) Perimeter = 2(10 cm) Perimeter = 20 cm

So the perimeter of the rectangle is 20 cm.

Units of Perimeter Perimeter is measured in the same units as the sides of the shape. For example, if the sides of a square are measured in centimeters, then the perimeter of the square will be measured in centimeters.

Perimeter of Common Shapes Here are some common shapes and their perimeter formulas:

Square: Perimeter = 4s (s is the length of one side) Rectangle: Perimeter = 2(l + w) (l is the length and w is the width) Triangle: Perimeter = a + b + c (a, b, and c are the lengths of the sides) Circle: Perimeter = 2πr (r is the radius of the circle and π is pi, approximately 3.14)

Practice Exercise Now let’s practice calculating the perimeter of shapes.

## Calculate the perimeter of the following shapes:

1. Square with sides of 5 cm.
2. Rectangle with a length of 8 cm and a width of 3 cm.
3. Triangle with sides of 6 cm, 8 cm, and 10 cm.
4. Circle with a radius of 4 cm.