what is cyclic quadrilateral

A cyclic quadrilateral, also known as an inscribed quadrilateral, is a four- sided polygon 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. The center of the circle is known as the circumcenter, and the radius of the circle is known as the circumradius. A key property of a cyclic quadrilateral is that the sum of the opposite angles is always supplementary, totaling 180 degrees. In other words, the sum of the angles at the vertices of a cyclic quadrilateral is always 360 degrees. Cyclic quadrilaterals have various properties and theorems that are useful in geometry and trigonometry