Answer: OPTION A.
Step-by-step explanation:
Observe the figure attached.
The first step is the find "a". In order to find this side, we need to use this Trigonometric Identity:

In this case:

Then, substituting values and solving for "a", we get:

Now we must apply this Trigonometric Identity:

In this case:

Then, substituting values and solving for "x", we get:
