Evaluate integral using substitution

Col Musstard
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Homework Statement


evaluate using substitution
Integral [cos^-1 x]/sqrt[1-x^2] dx

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The Attempt at a Solution


I am just starting with integration and I am getting frustrated with this problem. If someone could show me how to setup and start this problem so I could attempt to continue by reading instructions from my textbook it would be greatly appreciated
 
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Hint: What's the derivative of cos^{-1} x?
 
that is -1/sqrt[1-x^2] isn't it
 
Yup. Note that it's the other part of the integrand, so that means you should use a substitution.
 
so u=cos^-1x. therefore du=-1/sqrt[1-x^2] dx
is this correct so far?

I got -[[cos^-1x]^2]/2 +c hope its right, thanks for the help
 
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Yes, that's the correct answer. You can always differentiate what you got and see if you get back the integrand.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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