The answer is letter C. symmetric
Answer:

Step-by-step explanation:
Given expression:

The given expression needs to be simplified to the form 
Applying the exponents rule to simplify.

Writing all numbers as product of 3.
⇒ 
Writing each in exponents form.
⇒ 
Using power of a power rule ![[\ (a^x)^y=a^{xy}\ ]](https://tex.z-dn.net/?f=%5B%5C%20%28a%5Ex%29%5Ey%3Da%5E%7Bxy%7D%5C%20%5D)
⇒ 
Using multiplication rule of exponents ![[\ a^x\times a^y=a^{x+y}\ ]](https://tex.z-dn.net/?f=%5B%5C%20a%5Ex%5Ctimes%20a%5Ey%3Da%5E%7Bx%2By%7D%5C%20%5D)
⇒ 
⇒ 
So we have 
∴ 
Given:
In the given circle O, BC is diameter, OA is radius, DC is a chord parallel to chord BA and
.
To find:
The
.
Solution:
If a transversal line intersect two parallel lines, then the alternate interior angles are congruent.
We have, DC is parallel to BA and BC is the transversal line.
[Alternate interior angles]


In triangle AOB, OA and OB are radii of the circle O. It means OA=OB and triangle AOB is an isosceles triangle.
We know that base angles of an isosceles triangle are congruent.
[Base angles of an isosceles triangle]


In triangle AOB,





Therefore, the measure of angle AOB is 120 degrees.