so angle A and B are on what I call the z-angles which are normally equal in that if you view the parallel lines horizontally you will see the form of a z and the corners of it are equal that said you equate both of them to get x
It all depends upon what other things are given If hypotenuse is not given, in cosine or reciprocals are useless. In that case only tan and cot will be equally convenient if adjacent sides are given.
