Question

B

А

С

T

D

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In circle T, m AB = (3x + 9° and mCD = (11x – 71).

What is the measure of AB?

61°

37°

10°

39°

Answer 1

D. 39°

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.