A concave (non-convex) polygon

figures of this sort are intended to be excluded and it is implicitly assumed that a polygon is to be convex. Thus a convex polygon is a plane figure consisting of a finite region bounded by some finite number of lines, in the sense that the region lies entirely on one side of each line. The exterior angles of the polygon shown below are those marked,

Exterior angles of a convex polygon

and the sum of the exterior angles is always equal to 360°. The sum of the interior angles of an n-sided convex polygon equals 2n−4 right angles. In a regular convex polygon, all the sides have equal length and the interior angles have equal size; and the vertices are concylic.

Table of polygons' names