Generally, the word **polygon** is used to refer to a two dimensional construction that encloses a space using straight lines. Regular polygons have sides that are of equal length and have equal angles between each side. [Concave polygon]?s have at least one internal angle that is greater than 180°, whereas convex polygons have all internal angles less than 180°. A cyclic polygon has all of its vertexes lying on the same circle. A polygon can belong to several classifications simultaneously; a square is a regular, convex, cyclic polygon, for example.

'Poly-' is from the Greek word for 'many' and '-gon' is a Greek combining form meaning 'angle'. Strictly speaking, every polyhedron is also a polygon as is every polytope, since they all have angles.

Regular Polygons

Name | Sides | Angle* |
---|---|---|

Triangle | 3 | 60° |

Square | 4 | 90° |

Pentagon | 5 | 108° |

Hexagon? | 6 | 120° |

Septagon | 7 | 128.57° |

Octagon | 8 | 135° |

Nonagon | 9 | 140° |

Decagon | 10 | 144° |

Hectagon | 100 | 176.4° |

Megagon | 10^{6} | 180.° (approx.) |

Googolgon | 10^{100} | 180.° (approx.) |

* Angle= 180°-(360°/ Sides )