I don't know what your specific problem is, but here's an example.
Suppose I was given...... cos(x) = 1/2 , [0 < x < 720]
This says I want to find all the angles from 0 degrees to 720 degrees - inclusive - where the cos(x) = 1/2
The answer is [60, 300, 420, 660], because these are all the angles in that interval that have a cosine value of 1/2.
I hope that helps.
If you have a specific problem, feel free to submit it!!