# Polygon Photo by: John Takai

A polygon is a geometric figure in two dimensions with three or more sides. The name comes from two Greek words, poly, meaning "many," Different types of polygons. (Reproduced by permission of
The Gale Group
.)

and gon, meaning "angle." A polygon always has as many angles as it has sides. And in general, polygons are named to indicate the number of sides or angles they contain. Thus, a hexagon has six ( hexa- means "six") sides and six angles.

## Terminology used in describing polygons

### Parts and properties of polygons.

Side: Any one of the straight lines that make up the polygon.

Vertex: A point where any two of the sides of a polygon meet to form an angle.

Angle: A figure formed by the intersection of two sides.

Diagonal: A line that joins any two nonadjacent (not next to each other) vertices.

Perimeter: The sum of the length of all sides.

Area: The space enclosed within the polygon.

### Types of polygons.

Equilateral: A polygon in which all sides are equal in length.

Equiangular: A polygon in which all angles are the same size.

Regular: A polygon that is both equilateral and equiangular.

## Examples of polygons

The most common kinds of polygons include:

Parallelogram: A quadrilateral (four-sided figure) in which both pairs of sides are parallel and equal.

Rhombus: A parallelogram in which all four sides are equal.

Rectangle: A parallelogram in which all angles are right angles.

Square: A rectangle in which all four sides are equal.