Hello, I'm having some trouble completing a Fourier series question.(adsbygoogle = window.adsbygoogle || []).push({});

We have f(x)=Cos(x), for abs(x)≤π/2

f(x)=0, for π/2≤abs(x)≤π

period=2π

and then show that the Fourier series f(x) reads

http://img71.imageshack.us/img71/3424/84335314oi1.jpg [Broken]

now I can get the 1/π and the sum, as a_{n}=

http://img71.imageshack.us/img71/1703/eq2hn6.jpg [Broken]

and working through from there, the only part I'm having trouble with is the origin of the half cos(x) term. As far as I'm able to apply the fourier series I don't see where it comes from. (B_{n}must equal 0 right?)

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# Homework Help: Fourier Series of Cos(x)

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