Hello!
This problem is about relating trigonometric values to an unknown side.
We are given an angle side, and we can determine that another angle made would be a 90 degree angle.
Meaning we could solve for the third unknown angle by knowing that the interior angles of a triangle add up to 180 degrees.
After knowing this, we could use the law of sines, which states that the ratio of a side and the sin of its opposite angle are equal to any other ratio.
Make sure to be in degrees when putting this in a calculator.
Hope this helps!