Option C:
The measure of arc CD is 40°.
Solution:
Given data:
m∠X = 11° and m(arc AB) = 18°
To find the measure of arc CD:
We know that,
<em>Angle formed by two intersecting secants outside the circle is equal to half of the difference between the intercepted arcs.</em>
Multiply by 2 on both sides.
22° = arc CD - 18°
Add 18° from both sides.
40° = arc CD
Switch the sides.
arc CD = 40°
Hence the measure of arc CD is 40°.
Option B is the correct answer.