Question

CB is a tangent from C to the circle and BA is a diameter. angle AOC =120degree. Find angle BCO. (a)30° (b)40° (c)35° (d)25°​

Answer 1

Answer:

30°

Step-by-step explanation:

since CB is a tangent tto the circle we can say,

CB perpendicular to BA

ie <CBA = 90°

Given that <AOB = 120°

:. <COB = 180°- 120°=60° [linear pair]

Since COB is a triangle, we know that sum of all angles is 180°

:. <CBO + <COB + <BCO = 180°

=> 90° + 60° + <BCO = 180°

ie 150°+<BCO = 180°

:. <BCO = 180°-150° = 30°