|Class 9 Maths Circles||Cyclic Quadrilateral|
A quadrilateral ABCD is called cyclic if all the four vertices of it lie on a circle
Theorem 11: The sum of either pair of opposite angles of a cyclic quadrilateral is 180º.
In the figure, if ABCD is cyclic quadrilateral then ∠A’ + ∠C’ = ∠B’ + ∠D’ = 1800
Converse Theorem 12: If the sum of a pair of opposite angles of a quadrilateral is 180º, the quadrilateral is cyclic
In the figure, if ∠A’ + ∠C’ = ∠B’ + ∠D’ = 1800 then ABCD is cyclic quadrilateral
Refer ExamFear video lessons for Proof of this theorem