Library/Geometry/Plane geometry/Polygons/Polygons (other)

Polygons (other)

Overview
Important

A polygon is a closed plane figure formed by a finite number of straight line segments connected end-to-end. Beyond common regular polygons, there are many types of polygons, such as irregular polygons (not all sides or angles are equal), concave polygons (at least one interior angle is greater than 180°), and complex (self-intersecting) polygons.

Important properties

  • The sum of the interior angles of an n-sided polygon is (n−2)×180∘(n-2) \times 180^\circ.

  • A convex polygon has all interior angles less than 180°; a concave polygon has at least one angle greater than 180°.

  • Irregular polygons have sides and/or angles that are not all equal.

  • A simple polygon does not cross itself; a complex polygon does.