Here's a hint -- there are two places between 0 and 360 degrees where cos(theta) = -sin(theta). Can you see that at 45 degrees cos(theta) = sin(theta)? For this angle you are in quadrant 1, where both sin and cos are positive. But what about other quadrants where sin and cos have opposiite signs? I trust this helps - now post back with what you think the answer is.