Formula of the area of triangle
A=(1/2)a*b*sin(C)
a, b - sides
C- an angle between sides a and b.
Probably, this question means that you need to know sin of the angle.
Answer:
the answer is A
Step-by-step explanation:
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.