Q5 of 100 Page 17

If ABCD is a cyclic quadrilateral in which AD||BC (fig. 16.180). Prove that ∠B=∠C.

Since, ABCD is a cyclic quadrilateral with AD ‖ BC

Then,


∠A + ∠C = 180o (i) (Opposite angles of cyclic quadrilateral)


And,


∠A + ∠B = 180o (ii) (Co. interior angles)


Comparing (i) and (ii), we get


∠B = ∠C


Hence, proved


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