I am having some difficulty with the following ACT practice problem:
For X, an angle whose measure is between 270° and 360°, cosX=5/13. Which of the following equals tanX? A. -5/12 B. -5/13 C. 5/13 D. 5/12 E. 12/13
The book I am using provides the answer and an explanation, but the explanation uses process of elimination to find the answer without actually describing a method of solving the problem. I would like to understand how to actually find the answer. Can someone lend a helping hand?