Need help with complex problems!! I have trouble with a residue problem: Integral -inf --> inf sin(ax)/(x^2 + 4x + 5) As both it's poles contains both a real and a complex side, the sin(ax) part gets very ugly when I try to calculate it's residues. And I get a complex answere! Do I just ignore the complex part of the answere, and why? Also, I can't figure out how to make a laurentseries out of: 1/(1-cos(x)) Thanx for any help!!