Question

A,B and C are three points on a circle with centre O such that angle BOC=30 degree and angle AOB=60 degree.If D is a point on the circle other than the arc ABC,find angle ADC.​

Answer 1

angle AOC=angle AOB +angle BOC

= 60°+30°

= 90°

angle AOC is the angle at the center and angle ADC is

the angle at the circumference

angle ADC = ½ angle AOC = ½ ( 60°+30°) = 45°