What is a Regular Polygon?
A 2-dimensional enclosed figure made by joining 3 or more straight lines is called a polygon. Polygons are also known as ‘flat figures’.
Polygon Not a Polygon Not a Polygon (straight sides) (has a curve) (open, not closed) A polygon having equal sides and equal angles is a regular polygon.
Parts of a Regular Polygon
A regular polygon has three parts:
The interior angle is the angle formed within the enclosed surface of the polygon by joining the sides.
Different Regular Polygons
The names of the regular polygons come from the number of sides they have.
| Name | Figure | Sides | Interior Angle |
| Equilateral triangle |  | 3 equal sides | Each angle is 60° |
| Square |  | 4 equal sides | Each angle is 90° |
| Pentagon |  | 5 equal sides | Each angle is 108° |
| Hexagon |  | 6 equal sides | Each angle is 120° |
| Heptagon |  | 7 equal sides | Each angle is 128.57° |
| Octagon |  | 8 equal sides | Each angle is 135° |
| Fun Facts about Polygon – A circle is a regular 2D shape but it is not a polygon because it does not have any straight sides. Each angle of a regular polygon can be calculated by the given formula:  where n is the number of sides in the regular polygon. |
