Class 9 Maths Circles Cyclic Quadrilateral

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



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