වෘත්ත චතුරස්‍ර — සා/පෙළ ගණිතය

A cyclic quadrilateral is a quadrilateral whose four vertices all lie on a single circle. This circle is called the circumcircle of the quadrilateral. Every vertex of the quadrilateral is on the circumference of the circle. Not every quadrilateral is cyclic; only those with special angle properties can be inscribed in a circle.