Manipal Engineering Manipal Engineering Solved Paper-2010

  • question_answer
    The value of the integral\[\int_{\pi /2}^{3\pi /2}{[\sin x]dx}\], where \[[\cdot ]\]denotes the greatest integer function, is

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

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

    C) \[0\]                     

    D)        \[\pi \]

    Correct Answer: B

    Solution :

    \[\int_{\pi /2}^{3\pi /2}{[\sin x]}dx=\int_{\pi /2}^{\pi }{[\sin x]}\,\,dx+\]                 \[\int_{\pi }^{3\pi /2}{[\sin x]}\,\,dx\]                 \[=\int_{\pi /2}^{\pi }{0\,\,dx}+\int_{\pi }^{3\pi /2}{(-1)\,\,dx}=-[x]_{x}^{3\pi /2}\]                 \[=-\left( \frac{3\pi }{2}-\pi  \right)=-\frac{\pi }{2}\]


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