# Cyclic quadrilateral (Length of the diagonal opposite angle B)

## Description

In Euclidean geometry, a cyclic quadrilateral or inscribed quadrilateral is a quadrilateral whose vertices all lie on a single circle. This circle is called the circumcircle or circumscribed circle, and the vertices are said to be concyclic. In a cyclic quadrilateral with successive vertices A, B, C, D and sides a = AB, b = BC, c = CD, and d = DA, the lengths of the diagonals p = AC and q = BD can be expressed in terms of the sides.

Related formulas## Variables

p | Length of the diagonal opposite angle B (m) |

a | Length of the side of the cyclic quadrilateral ( AB) (m) |

c | Length of the side of the cyclic quadrilateral (CD) (m) |

b | Length of the side of the cyclic quadrilateral (BC) (m) |

d | Length of the side of the cyclic quadrilateral (DA) (m) |