Answer:
D. 39°
Step-by-step explanation:
mAB = (3x + 9°)
mCD = (11x – 71)
From the diagram: |AB|=|CD|
Since arcs AB and CD are subtended by a chord of equal length.
mAB=mCD
3x + 9°=11x – 71°
Collect like terms to solve for x
11x-3x=9°+71°
8x=80°
x=10°
Therefore, the measure of AB:
mAB = (3x + 9°)
=3(10)+9
=30+9
=39°
The correct option is D.
