Question - Find the Fourier series for f(x) = |cos(x)| in the interval (-π, π).

Right, I attempted the question and the integration that followed. I'm having trouble in the integration itself..

Firstly I found that f(x) is an even function, so the sine term(b

as
and similarly so for a

I computed a

Right, I attempted the question and the integration that followed. I'm having trouble in the integration itself..

Firstly I found that f(x) is an even function, so the sine term(b

_{n}) of the Fourier expansion would be zero and that I can use a property of integration to write_{n}.I computed a

_{0}to be zero, but the trouble is, I'm getting a_{n}to be zero too, and if that is so, there will be no Fourier series!! Could someone please point out my mistake?
Last edited by a moderator: