If all the four vertices of a quadrilateral ABCD lie on the circle and m∠D = 60°, then m∠B = ____
(A) 30°
(B) 90°
(C) 120°
(D) 100°
Correct option (C) 120°
Explanation:
ABCD is a cyclic quadrilateral
∴ ∠B + ∠D = 180°
( Sum of opposite angle = 180°)
60 + ∠B = 180°
∠B = 120°.
