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## Homework Statement

Hi I'm stuck with the following problem:

Find the fourier series of:

f(t) = { -sint for -pi < t < 0 and sint for 0 < t < pi }

## The Attempt at a Solution

since they are both even functions I expanded both using the cosine series and I get two integrals which are the same if i swap the limits of integration around. So I add them together and I get:

1/pi [ ʃ sin(t)cos(nx)] in the limits of -pi to pi

Im trying to use a trig identity so that i can then integrate it but this is where I'm a bit lost.

Any help will be greatly appreciated.