1.

The value of `int_(0)^(a) sqrt((a-x)/x )` dx isA. `(a)/(2)`B. `(a)/(4)`C. `(pia)/(2)`D. `(pia)/(4)`

Answer» Correct Answer - C
Let ` l = int_(0)^(a) sqrt(a-x)/xdx`
Put x = a `sin^(2) theta rArr dx = 2a sin theta cos theta d theta `
` :. i = int _(0)^(pi//2) sqrt((cos^(2)theta)/(sin^(2)theta)). 2a sin theta cos theta d theta `
` = 2a int_(0)^(pi//2) cos^(2) theta d theta `
` = 2a int _(0)^(pi//2) [ (1+cos 2theta)/2] d theta = 2a [ theta/2 + (sin 2theta)/4]_(0)^(pi//2)`
` = 2a xx1/2 xx pi/2 = (pia)/2`


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