In fig., if <OAB=40∘, the < ACB is equal to:
50∘
40∘
60∘
70∘
Since OA = OB Therefore ∠OAB=∠OBA=40∘ Now, ∠AOB=180−(40+40)=100∘ (By angle sum property of a triangle) ⇒∠ACB=50∘