# Perimeter

The perimeter of a polygon (or any other closed curve, such as a circle) is the distance around the outside.

Here are some formulas for the perimeters of common plane figures.

 Perimeter Formulas Shape Formula Variables Square $P=4s$ $s$ is the length of the side of the square. Rectangle $P=2L+2W$ $L$ and $W$ are the lengths of the rectangle's sides (length and width). Triangle $a+b+c$ $a,b$ , and $c$ are the side lengths. Right Triangle, with legs $a$ and $b$ (see Pythagorean Theorem ) $P=a+b+\sqrt{{a}^{2}+{b}^{2}}$ $a$ and $b$ are the lengths of the two legs of the triangle Circle $P=C=2\pi r=\pi d$ $r$ is the radius and $d$ is the diameter.