1. The problem statement, all variables and given/known data I have the following complex numbers : -3,18 +4,19i I must put it in polar form. 2. Relevant equations r=(a^2+b^2)^(1/2) cos x = a/r sin x = b/r 3. The attempt at a solution I was able to find with cos x = a/r that the x = 127,20 But when I do it with sin x = b/r I obtain like 52 degrees. I know that I Must obtain 127,20 for BOTH. Why isnt it working ?