**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’.

**Not**a Polygon

**Not**a 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° |

- 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. |