# Perimeter

## Definition

The perimeter of a geometric figure is the distance around the outside of the figure. Perimeter is often denoted by P. The perimeter of a circle is called its circumference.

## Formulas

• Rectangle: $2(l+w)$, where $l$ is the length and $w$ is the width.
• Square: $4s$, where $s$ is the side length. <follows from rectangle>
• Circle - $2\pi r$, where $r$ is the radius.
• Regular polygon with $n$ sides: $ns$, where $s$ is the side length.
• Polygon with $q$ sides: $\sum_{z=1}^{q} a_z$, where $a_i$ are the lengths of the sides of the polygon.