JCECE Engineering JCECE Engineering Solved Paper-2002

  • question_answer
    \[\int_{0}^{\pi /2}{x\,\,\sin \,\,x\,\,dx}\]is equal to:

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

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

    C) \[\pi \]                                 

    D)  \[1\]

    Correct Answer: D

    Solution :

    Let          \[I=\int_{0}^{\pi /2}{x\sin x\,\,dx}\]                 \[=[-x\cos x+\int{\cos x\,\,dx]_{0}^{\pi /2}}\]                 \[=[-x\cos x+\sin x]_{0}^{\pi /2}\]                 \[=\left[ -\frac{\pi }{2}(0)+1-(0+0) \right]\]                 \[=1\]


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