Polygon

A polygon is a plane figure of 3 or more sides.

Here are some polygons:

Sides	Name	Example
3	triangle
4	quadrilateral
5	pentagon
6	hexagon
8	octagon
12	dodecagon

A polygon where all the sides are the same length is a regular polygon. All the figures above, except the quadrilateral, are regular polygons. Notice how the more sides a regular polygon has the more it looks like a circle!
The interior angles of a polygon:
Each angle A = 180 (N - 2) / N degrees where N is the number of sides.

Now, here's a problem for you:
What is the measure of an interior angle of a regular octagon?

Octagon interior angle = ______ degrees.