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# Integral substitution makes both limits zero Watch

1. I'm having a problem with this integral, see the attached pdf, I have written up my problem in latex, if you have any thoughts I would be glad to hear them.

Cheers.
Attached Images
2. Bad Integral Substitution.pdf (87.1 KB, 60 views)
3. Looking at the Wikipedia article on integration by substitution http://en.wikipedia.org/wiki/Integra...y_substitution (particularly the second paragraph) then your 'g' is which is not monotonically strictly increasing on [0,2pi] so you can't use it as a substitution.

You could probably work around this issue by splitting up your integral into several integrals over different intervals in [0,2pi] but I haven't tried this myself.
4. Yes thanks I think that should work.
5. The problem is in the last line for the integral

The square root part is always taken as positive. But is negative from

You last integral should be:

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