Answer:
The correct answer is D. 69
Explanation:
Let's recall that if an exterior angle has its vertex where two rays share an endpoint outside a circle, the measure of that exterior angle is found by dividing the difference between the measures of the intercepted arcs by two.
Therefore, we have:
x = (Measure of arch CD - Measure of arch BD)/2
Replacing with the real values:
x = (210 - 72)/2
x = 138/2 = 69°
The correct answer is D. 69