A rational answer 2 + 2 = 4
4x + 6 = 9 is the equation
A Google or Bing search box can be your friend, if you don't have a calculator with inverse trig functions. Most calculators that have trig functions also have the inverse functions, usually after a 2nd or "shift" key. Often, there is a mode setting for degrees or radians.
arcsin(0.33) ≈ 19°
arccos(0.47) ≈ 62°
arctan(1.21) ≈ 50°
arcsin(0.82) ≈ 55°