# Trignometric Polynomial complex form

by phillyj
Tags: complex, fourier transform
 P: 30 Hi, I'm trying to learn Fourier transforms by myself. I'm a bit confused about how the trignometric polynomial complex form was derived. I'm refering to this: http://en.wikipedia.org/wiki/Trigonometric_polynomial Now, I haven't taken complex analysis so I only know the basics. I used Euler's formula and got that far but I'm not sure what to do next. Thanks
 Mentor P: 15,960 Substitute $$\cos(nx)=\frac{e^{inx}+e^{-inx}}{2}, ~\sin(nx)=\frac{e^{inx}-e^{-inx}}{2i}$$ in the series and rearrange everything. This should give you the required form.

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