1. The problem statement, all variables and given/known data Find the cosine Fourier transform of the function f(t)=e-at 2. Relevant equations 3. The attempt at a solution F(w)=(2/π)0.5∫dt e-atcos(wt) The integral is from 0 to +∞ Using euler's formula I got the result F(w)=(2/π)0.5( eit(w-a)/i(w-a) - e-it(w+a)/i(w+a) ) I don't know what to do from here... I can't just substitute! If anyone could point me in the right direction I'd appreciate!