Plzz ans fast!!! Q). If fig, if ∠ O A B = 40 ° , then find ∠ A C B . Share with your friends Share 0 Abhishek Jha answered this Dear Student, Here is the solution of your asked query: Considering O as the center of the circle.OA=OB {radius of circle}So, ∠OBA=∠OAB = 40° {Angles opposite to equal sides are equal}Now in △AOB, we have;∠OBA+∠OAB+∠AOB=180°⇒40°+40°+∠AOB=180°⇒∠AOB=180°-80°=100°And we know that angle substended by an arc at the center is double the angle sustended by it at any point on the circle.So, ∠ACB=2∠AOB = 2×100°=200°Therefore, ∠ACB=200° Regards 0 View Full Answer