In the given figure, if ∠OAB=40∘, then ∠ACB = ___.
Note that OA = OB=radius of the circle.
Since angles opposite to equal sides are equal, ∠OAB=∠OBA=40∘.
Using angle sum property in △OAB, we have
Since the angle subtended by an arc at the centre is double the angle subtended by it at any remaining part of the circle, we have