JEE Main & Advanced Mathematics Definite Integration Question Bank Properties of Definite Integration

  • question_answer
    The value of \[\int_{0}^{2\pi }{{{\cos }^{99}}x\,dx}\] is

    A)                 1             

    B)                 \[-1\]

    C)                 99          

    D)                 0

    Correct Answer: D

    Solution :

               Let \[I=\int_{0}^{2\pi }{{{\cos }^{99}}x\,dx.}\]                    Then \[I=2\int_{0}^{\pi }{{{\cos }^{99}}x\,dx,\,\,\,\{\because {{\cos }^{99}}(2\pi -x)={{\cos }^{99}}x\}}\]                    Now, \[\int_{0}^{\pi }{{{\cos }^{99}}x\,dx\,=0,\,\,\{\because {{\cos }^{99}}(\pi -x)=-{{\cos }^{99}}x\}}\]                                 \[\therefore \,\,I=2\times 0=0\].


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