Cyclic quadrilateral (cosine of an angle)

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. A convex quadrilateral ABCD is cyclic if and only if its opposite angles are supplementary. The cosine of an angle of a cyclic quadrilateral can be calculated by the sides of the quadrilateral.

Related formulas

Variables

AAngle of the quadrilateral between sides AB and AD (degrees)
aLength of the side of the cyclic quadrilateral (AB) (m)
dLength of the side of the cyclic quadrilateral (DA) (m)
bLength of the side of the cyclic quadrilateral (BC) (m)
cLength of the side of the cyclic quadrilateral (CD) (m)