Perimeter

Definition

The perimeter of a geometric figure is the total length around its boundary. It is calculated by summing the lengths of all its sides.

5 Must Know Facts For Your Next Test

1. The perimeter of a rectangle can be calculated using the formula $P = 2(l + w)$ where $l$ is the length and $w$ is the width.
2. For a triangle, the perimeter is simply the sum of the lengths of its three sides.
3. The perimeter of a circle is known as its circumference and is calculated using $C = 2\pi r$ where $r$ is the radius.
4. In algebraic problems, perimeters are often used to set up equations that represent real-world scenarios such as fencing a yard or framing a picture.
5. Perimeter calculations can help in solving inequalities by providing constraints for variable dimensions.

Review Questions

• How do you calculate the perimeter of a rectangle with length 5 units and width 3 units?
• What formula would you use to find the perimeter of an equilateral triangle with side length $s$?
• If given an inequality involving the perimeter of a square, how would you set up your equation?

Related terms

Area: The amount of space inside a two-dimensional boundary. It is measured in square units.

Circumference: The distance around a circle, equivalent to its perimeter. Calculated as $C = 2\pi r$.

Polygon: A closed figure with many sides. The perimeter is found by adding up all side lengths.