Correct option is B
Given:ABCD is a cyclic quadrilateral, AB is the diameter of the circle
,∠ADC=140∘
Concept used:In a cyclic quadrilateral, opposite angles are supplementary:
∠ADC+∠ABC=180∘
Angle subtended by the diameter in a semicircle is a right angle:
∠ACB=90∘
Solution:
∠ABC∠ACB∠BAC=180∘−∠ADC=180∘−140∘=40∘=90∘=180∘−∠ABC−∠ACB=180∘−40∘−90∘=50∘
Correct answer is (b):
50∘