Pentagons

A pentagon is a five-sided polygon. If it is regular, all its sides and angles are equal. The sum of the interior angles of any pentagon is 540°, calculated by the formula $(n-2) \times 180°$ where $n$ is the number of sides.

Important properties

• A regular pentagon has all sides equal and all angles equal (each angle is 108°).

• The sum of the interior angles is 540°.

• The sum of the exterior angles is always 360°.

• A pentagon can be convex (all angles less than 180°) or concave (at least one angle greater than 180°).