# Brianchon theorem

If an hexagon^{} $ABCDEF$ (not necessarily convex) is inscribed^{} into
a conic (in particular into a circle), then the three diagonals
$AD,BE,CF$ are concurrent^{}. This theorem is the dual of Pascal
line^{} theorem. (C. Brianchon, 1806)

Proof:It follows by duality.

Title | Brianchon theorem^{} |
---|---|

Canonical name | BrianchonTheorem |

Date of creation | 2013-03-22 14:04:29 |

Last modified on | 2013-03-22 14:04:29 |

Owner | vmoraru (1243) |

Last modified by | vmoraru (1243) |

Numerical id | 7 |

Author | vmoraru (1243) |

Entry type | Theorem |

Classification | msc 51-00 |