Polygons are closed plane figures bounded by three or more line segments. In the world of geometry, polygons abound. The term refers to a multisided geometric form in the plane. The number of angles in a polygon always equals the number of sides.

Polygons are named to indicate the number of their sides or number of noncollinear points present in the polygon. For example, a triangle has three sides and three vertices, a rectangle has four sides and four vertices; others: pentagon, five and five; hexagon, six and six; heptagon, seven and seven; octagon, eight and eight; nonagon, nine and nine; decagon, ten and ten; and an n-gon has n number of sides and n number of vertices.

A square is a special type of polygon, as are triangles, parallelograms, and octagons. The prefix of the term, poly comes from the Greek word for many, and the...