1. Find the sinusoids represented by these phasors: (a) I = -3 + j4 A 3. well to convert first to polar they got the following they didnt show their steps: I = 5 <126.87 then they said i(t) = 5 cos(wt + 126.87) What I dont get is the fact that how they got 126.87 to get 5 i just take 3 and 4 sum their squares and take the square root. to find the angle i would do tan-1(y/x) = tan-1(4/-3)=-53.13 ok since its tangent you may say u can add 180 and it is the same answer which is what they did -53.13 +180=126.87 but my question is WHY. why do they add the 180 if its the same thing. Whats the use. I would just leave my final answer as i(t) = 5cos(wt - 53.13) why add 180?