Point O is the center of the circle in the diagram. What is m∠BCA?

Question

Select the correct answer.

A. 

80°

B. 

75°

C. 

70°

D. 

65°

Answer 1

measure of exterior angle formed by two tangents is 1/2 the difference of the measures of the intercepted arc.

m<BOA = 360 - 250 = 110, so the closer arc intercepted by that central angle is 110.

The further away intercepted arc will be 360 - 110 = 250.

m<BCA = 1/2 ( difference of intercepted arcs) = 1/2 (250 - 110) = 70 (C)