what is cyclic quadrilateral ? please explain it clearly .

Definition of Cyclic Quadrilateral

• If a quadrilateral has all of its vertices lying on a circle, then it is known as a Cyclic Quadrilateral.

More about Cyclic Quadrilateral

• In a cyclic quadrilateral:
  1. Opposite angles are supplementary.
  2. Exterior angles are equal to the opposite interior angles. 
  3. The product of the two diagonals is equal to the sum of the products of opposite sides.

Example of Cyclic Quadrilateral