JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2005

  • question_answer
        Evaluate\[\int_{0}^{\pi /2}{\frac{\sqrt{\sin x}}{\sqrt{\sin x}+\sqrt{\cos x}}}dx\]:

    A)  \[\frac{\pi }{4}\]                                             

    B)  \[\frac{\pi }{2}\]

    C)  zero                                     

    D)  1

    Correct Answer: A

    Solution :

                    \[I=\int_{0}^{\pi /2}{\frac{\sqrt{\sin x}dx}{\sqrt{\cos x}+\sqrt{\sin x}}}\]                         ...(i) \[I=\int_{0}^{\pi /2}{\frac{\sqrt{\sin (\pi /2-x)}}{\sqrt{\cos (\pi /2-x)}+\sqrt{\sin (\pi /2-x)}}}dx\] \[I=\int_{0}^{\pi /2}{\frac{\sqrt{\cos x}}{\sqrt{\sin x}+\sqrt{\cos x}}}dx\]                              ?.(ii) on adding equation (i) and (ii)                 \[2I=\int_{0}^{\pi /2}{dx}\] \[\Rightarrow \]               \[I=\frac{\pi }{4}\]


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