- #1
DanPF
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Homework Statement
Hi
First of all this a textbook question from Stroud Advanced Engineering Mathematics, solution is given, but no steps are shown.
A question I just can't seem to solve at the moment, as below.
A function f(x) is defined by [tex]f(x) = \pi - x:0 < x < \pi[/tex]
[tex] f(x + 2\pi) = f(x)[/tex]
Express the function as a half range cosie series
Homework Equations
Im at a loss of how to start this question, I've been doing fine when they haven't included pi in the function itself.
I know as its wanted as a cosine series I'll have to make it resemble an even function and thus my a0 and an terms can be
[tex]2/\pi \int^{\pi}_{0}\pi - x dx[/tex][tex]\stackrel{2}{\pi}\int^{\pi}_{0}\pi - x\:cosnx:dx[/tex]
So my main question is really how I remove pi. I've tried taking it out as a constant which doesn't work, so I have a feeling I am not realising something
The final solution according to the book is
[tex] \pi/2 + 4/\pi\left\{cosx + 1/9:cos3x + 1/25:cos5x+ ...\right\}[/tex]
I keep getting [tex] -\pi^2[/tex] for a0
Thank you for reading and any help
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