# Octagon

polygon with eight sides

An octagon or 8-gon is a shape with 8 sides and 8 corners.

An octagon

## Regular octagon

All sides of a regular octagon are the same length. Each corner is 135°. All corners added together equal 1080°.

### Area

The amount of space a regular octagon takes up is

${\displaystyle {\text{Area}}=2(1+{\sqrt {2}})a^{2}.}$

a is the length of one of its sides.

Another way to write it is

${\displaystyle {\text{Area}}=2a^{2}({\sqrt {2}}+1).}$