# Real and Imaginary Parts of $\frac{\cos(z)}{(1-e^{ix})}$

Find

$$\mathrm{Re}\bigg(\frac{\cos(x+iy)}{(1-e^{ix})}\bigg)$$

and

$$\mathrm{Im}\bigg(\frac{\cos(x+iy)}{(1-e^{ix})}\bigg)$$

-
two things: first please learn to use Latex. I've fixed the post for you but its a lot neater to read when it's pretty. ;) second. can you show us what you've tried so far? maybe that will help us help you. –  franklin May 1 '13 at 20:09

Multiply the numerator and denominator by $1-e^{-ix}$ and you get a denominator that is real. Then you just have to find the real and imaginary parts of $\cos(x+iy)(1-e^{-ix})$.
Hint: Use $$\cos (z) = \frac{e^{iz}+e^{-iz}}{2}$$