First use Pythagorean theorem to find the length of the hypotenuse. Use . Since we know a and b we can plug in to find c. When we plug in we get: . When we solve this out we get 25 = c.
Now that we know the value of c, we also know sin(x) = . Using this we see that sin(x) = .
To get the exact degree value of x, take the inverse sin of :