Answer:
X is approximately 7.8.
Explanation:
You can use SOH-CAH-TOA to help figure out what function (sin, cos, tan) you need to use in order to figure out the missing side.
For this one, we can see the angle is pointing to the opposite side (x length), and we have been given the hypotenuse (18). So we want to use the sin function.
Using Pythagorean theorm, you can figure out the other side if need be :)
For reference: