# Octadecagon

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Octadecagon | |
---|---|

Rank | 2 |

Type | Regular |

Space | Spherical |

Notation | |

Coxeter diagram | x18o |

Schläfli symbol | {18} |

Elements | |

Edges | 18 |

Vertices | 18 |

Vertex figure | Dyad, length 2cos(π/18) |

Measures (edge length 1) | |

Circumradius | |

Inradius | |

Area | |

Angle | 160° |

Central density | 1 |

Number of pieces | 18 |

Level of complexity | 1 |

Related polytopes | |

Army | {18} |

Dual | Octadecagon |

Conjugates | Octadecagram, great octadecagram |

Abstract properties | |

Euler characteristic | 0 |

Topological properties | |

Orientable | Yes |

Properties | |

Symmetry | I_{2}(18), order 36 |

Convex | Yes |

Nature | Tame |

The **octadecagon** is a polygon with 18 sides. A regular octadecagon has equal sides and equal angles.

## Stellations[edit | edit source]

- 2-octadecagram
*(compound of 2 enneagons)* - 3-octadecagram
*(compound of 3 hexagons)* - 4-octadecagram
*(compound of 2 enneagrams)* - 5-octadecagram
- 6-octadecagram
*(compound of 6 triangles)* - 7-octadecagram
- 8-octadecagram
*(compound of 2 great enneagrams)*

## External links[edit | edit source]

- Bowers, Jonathan. "Regular Polygons and Other Two Dimensional Shapes".

- Wikipedia Contributors. "Octadecagon".