JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Fundamental Integration

  • question_answer
    If \[\int{\sqrt{2}\sqrt{1+\sin x}}\,\,dx=-\,4\cos (ax+b)+c\] then the value of (a, b) is [UPSEAT 2002]

    A)            \[\frac{1}{2},\,\frac{\pi }{4}\]

    B)            \[1,\,\frac{\pi }{2}\]

    C)            1, 1

    D)            None of these

    Correct Answer: A

    Solution :

               \[I=\int{\sqrt{2}\sqrt{1+\sin x}}\,dx\]\[=\sqrt{2}\int{\left( \sin \frac{x}{2}+\cos \frac{x}{2} \right)\,dx}\]              \[=2\int{\sin \left( \frac{\pi }{4}+\frac{x}{2} \right)\,dx=-\,4\cos \,\left( \frac{x}{2}+\frac{\pi }{4} \right)+c}\]                    On comparing, \[a=\frac{1}{2},\,b=\frac{\pi }{4}.\]


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