1.

`int_(0)^(1) sqrt((1-x)/(1+x)) dx=?`A. `(pi)/(2)+1`B. `(pi)/(2)-1`C. `-1`D. 1

Answer» Correct Answer - B
`I=int_(0)^(1)sqrt((1-x)/(1+x))dx=int_(0)^(1)(1-x)/(sqrt(1+x^(2)))`
`=int_(0)^(1)(1)/(sqrt(1-x^(2)))dx-int_(0)^(1)(x)/(sqrt(1-x^(2)))dx`
`=[sin^(-1)x]_(0)^(1)+int_(0)^(1)(t)/(t)dt`
where , `t^(2)=1-x^(2)rArrtdt =-x dx]`
`=(sin^(-1)-sin^(-1)0)+[t]_(1)^(0)=pi//2-1`


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