Evaluate: `int sqrt((1-x)/(1+x))dx`

Explanation

Substitute `sqrt{x}=sin t`
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x=sin ^{2} t `
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d x=2 sin t cos t`
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I=2 int sqrt{frac{1-sin t}{1+sin t}} sin t cos t d t`
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=2 int sqrt{frac{1-sin t}{1+sin t} times frac{1-sin t}{1-sin t}} sin t cos t d t`
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