# Integration - Im stumped

• Feb 26th 2009, 05:31 PM
Bedo
Integration - Im stumped
I should know this but I cannot figure it out.

The problem is.

integrate Cot[x]/Sqrt[Sin[x]] dx

I convert the Cot[x] into Cos[x]/Sin[x]

I assume this problem is done by u-substitution. I cant figure out what to set u = ?

Thanks for you help.
• Feb 26th 2009, 05:40 PM
Exiab
U sub value
Just set your U substitution with u=sin(x) and that will get you to the end, good luck.(Happy)
• Feb 26th 2009, 05:51 PM
aervid
you can do it without u substitution (unless it is required). Just make the bottom sinx^(3/2) and you should be able to do it no problem (Hi)... I personally dont like u substitution too much, too much work.
• Feb 26th 2009, 05:52 PM
Bedo
I have tried that but I get lost.

So here is where I am at.

Integral (Cos[x]/Sin[x])/Sqrt[Sin[x]] dx

Let u = sinx
du = cosx

I am not sure how the problem will look after the substitution.
• Feb 26th 2009, 06:00 PM
Bedo
I think I got it.

(-2)/Sqrt[Sin[x]] + C

I liked that idea of just combining the Sin's into sin^(3/2).

Thanks for the help everyone! (Clapping)
• Feb 26th 2009, 08:54 PM
aervid
yeah thats what I got (Happy)
• Feb 27th 2009, 02:16 AM
mr fantastic
Quote:

Originally Posted by aervid
you can do it without u substitution (unless it is required). Just make the bottom sinx^(3/2) and you should be able to do it no problem (Hi)... I personally dont like u substitution too much, too much work.

Personally I'd advise that a beginner should always attempt this sort of integral making the substitution suggested earlier.