There are several ways to classify polygons. They can be classified as convex and not convex; as regular or irregular. Polygons are also classified by how many sides they have. The following table lists the different types of polygons, with the name ande major characteristics of the polygons. We also point out that the number of diagonals can be obtained by the following formula: `D = n (n-3) // 2` and the amplitude of the internal angle can be calculated using the following formula: `A = 180 (n-2) // n` (for regular polygons only).

Name | Image | Number of sides | Number of diagonals | Internal Angle (regular polygon) |
---|---|---|---|---|

Triangle | 3 | 0 | 60º | |

Quadrilateral | 4 | 2 | 90º | |

Pentagon | 5 | 5 | 108º | |

Hexagon | 6 | 9 | 120º | |

Septagon | 7 | 14 | 128,6º | |

Octagon | 8 | 20 | 135º | |

Nonagon | 9 | 27 | 140º | |

Decagon | 10 | 35 | 144º | |

Hendecagon | 11 | 44 | 147,3º | |

Dodecagon | 12 | 54 | 150º | |

Tridecagon | 13 | 65 | 152,3º | |

Tetradecagon | 14 | 77 | 154,3º |

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