# Product of the diagonals in a convex quadrilateral(Bretschneider's formula for diagonals)

## Description

A quadrilateral is a polygon with four sides (or edges) and four vertices or corners. In any convex quadrilateral ABCD, the product of the two diagonals is related to the four sides AB, BC, CD, DA and to the two of the oppsosite angles of the quadrilateral.

Related formulas## Variables

p | One of the diadonals of the quadrilateral (m) |

q | The other diadonal of the quadrilateral (m) |

a | Side of the quadrilateral (AB) (m) |

c | Side of the quadrilateral (CD) (m) |

b | Side of the quadrilateral (BC) (m) |

d | Side of the quadrilateral (DA) (m) |

A | Angle of the quadrilateral (inside a and d) (m) |

C | Angle of the quadrilateral (inside b and c) (m) |