I'm having some problem in determining the phase of an exponential fourier series. I know how to determine the coefficient which in turn gives me the series after I multiply by [itex]e^-(jωt)[/itex] I can determine the amplitude by dividing the coefficient by 2 [itex]|Dn| = Cn/2[/itex] Now my question is how to determine the phase angle. My book only gives me [itex]ø=∠Dn[/itex] and it doesn't explain how they get the values. Do I have to expand Cn into its real and imaginary parts and then calculate the angle using tan^{-1}(-bn/an) as I would when using sines and cosines?