Hello, I recently run into a problem. Lets say I have the point (a,b) and (-a,-b). The, I know that θ_1 = atan(b/a) and θ_2 = atan((-b)/(-a)) = θ_1. But, what if I want to go back to Cartesian coordinates? If I assume r = 1, a = cos(θ_1) and b = sin(θ_1) while -a = cos(θ_2) and b = sin(θ_2). I am sure this is very simple and it has to do with the fact that the range of atan is (-π/2,π/2). But is there a way of getting back the -a? Could I just add π to the angle whenever a and b are negatives?