Sohcahtoa is used if there is a missing side of a triangle. just remember that soh means opposite over hypotenuse, cah means adjacent over hypotenuse, toa means opposite over adjacent. if jou knew where the adjacent, opposite side and hypotenuse located, then it will be easy to use sohcahtoa in solving the missing part of the triangle. but i think you can also use Pythagorean theorem. not really sure.