Inverse Trig. Functions (arcsin, arccos, arctan)

Arcsin:  http://www.rapidtables.com/math/trigonometry/arcsin.htm

Arccos: http://www.rapidtables.com/math/trigonometry/arccos.htm

Arctan: http://www.rapidtables.com/calc/math/Arctan_Calculator.htm

Arcsin = sin-1

        hypotenuse

           opposite

Arccos = cos-1

        hypotenuse

          adjacent

Arctan = tan-1

        adjacent

        opposite

It is important to know how to use the inverses.