Cyclic Quadrilateral is inscribed into a circle, whose vertices all lie on a circle.

The properties of Cyclic Quadrilateral in Circle Geometry are;

1. Opposite angles in a cyclic quadrilateral supplementary.

2. Exterior angle and its opposite angle are equal.

### Worked Examples of Cyclic Quadrilateral

(a) Prove that \(FADG\) is a cyclic quadrilateral.

(b) Prove that \(GA\) is a tangent to the circle through \(A\), \(B\), \(C\) and \(D\).