Question

in the given figure 0 is the centre of the circle and PA,PB are tangents to the circle .if angle APB=60degree,find angle ACB

Answer 1

In quad. AOBP
 <OBP + <OAP + <AOB + <APB = 360 degree
=>         90 + 90 + 60 + <AOB = 360
=>         <AOB = 120 degree 
Now,
           <AOB =2<ACB
=>          120 = 2<ACB
=>        <ACB = 60 degree