IntegrateI exapned sin4x and did some partial fractions stuff, but the answer which I get is not the back answerCode:`sinx/sin4x`

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- November 13th 2010, 12:36 AMice_syncerintegrate sinx/sin4x
Integrate

Code:`sinx/sin4x`

- November 13th 2010, 12:53 AMmr fantastic
integrate Sin[x]/Sin[4x] - Wolfram|Alpha

Click on Show steps. - November 13th 2010, 01:34 AMice_syncer
;D

- November 13th 2010, 03:49 AMtonio

Wolfram's steps look too frightening. I'd rather go for a trigonometric substitution:

, so with a little trigonometry:

, and we have an integral of a rational function.

Indeed this still is a nasty integral, but perhaps a little less messier than in the steps of the proposed solution

in Wolfram's...perhaps.

Tonio - November 13th 2010, 05:47 AMKrizalid
- November 13th 2010, 08:00 AMTheCoffeeMachine
Wolfram also made mess of the partial fractions:

If letting gives , then simply write:

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Thus our original integral evaluates to: