Solving Complex Integration with Residue Theorem

hedipaldi
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Homework Statement



use residue theorem to integrate sinh(ax)/sinh(xpi) from -infinity to +infinity, a is between -pi and pi

Homework Equations



residue theorem

3
. The attempt at a solution

i tried rectangular trajection through 0 and ia/pi with the function sinh(az)/sinh(zpi) and some other trajectories but it doesn't really work
 
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The residue theorem applies to integration over closed paths. What closed paths have you used?
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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