In the figure given below, O is the center of the circle, CA istangent at A and CB is tangent at B drawn to the circle.
If ∠ ACB=75∘, then ∠AOB= ______.
105∘
∠OAC=∠OBC=90∘
(∵The tangent at any point on a circle
is perpendicular to the radius throughthat point.)
∠OAC+∠OBC+∠ACB+∠AOB=360∘
(∵Sum of angles of a quadrilateral)
90∘+90∘+75∘+∠AOB=360∘
∠AOB=360∘−255∘=105∘
∠AOB=105∘