Sunday, May 13, 2012

`int_0^(1/sqrt(2)) arcsinx/sqrt(1-x^2) dx` Evaluate the definite integral

We have to evaluate the definite integral:


`\int_{0}^{1/\sqrt{2}}\frac{arc sinx}{\sqrt{1-x^2}}dx`


Let `t= arcsinx`


Differentiating both sides we get,


`\frac{1}{\sqrt{1-x^2}}dx=dt`                 (Since we know that `\frac{d}{dx}(arc sinx)=\frac{1}{\sqrt{1-x^2}}`



Now when x=0, t=0


and when      `x=1/sqrt(2)` , t= `\frac{\pi}{4}`   


Hence we have,



`\int_{0}^{1/\sqrt{2}}\frac{arc sinx}{\sqrt{1-x^2}}dx=\int_{0}^{\pi/4}tdt`



                      =`pi^2/32`

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