1. The problem statement, all variables and given/known data I am working through a calc 2 problem. I managed to get here without really completely understanding trig. There was a point in the problem where θ=Tan-1(-2/2) = -Pi/4. How does this work? 2. Relevant equations I do not know any relevant equations 3. The attempt at a solution I really have no clue. I have done research countless times.