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I have function $f(x)=|\cos(x)|, x≥0$ and like to derive its Laplace transform. I am told that $f(x+\pi)=f(x)$. Help me please.

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    If you just need the result without derivation: http://www.wolframalpha.com/input/?i=laplace+transform+abs%28cos%28x%29%292012-06-14
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    I see there is a formula for your function.2012-06-14
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    @in_wolfram_we_trust: Make me a detailed hint.2012-06-14
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    Sorry, I don't have one.2012-06-14
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    But You can look at @BabakSorouh answer below.2012-06-14

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Your function is periodic ($T=\pi$) so you can easily use the formula:

$L(f(x))=\frac{1}{1-e^{-sT}}\int_{0}^{T}e^{-sT}f(x)dx$

Note that your function is a piecewise function broken at $\frac{\pi}{2}$.

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    Nice!! :+) $\quad +1 \quad$2013-03-06