RAJASTHAN ­ PET Rajasthan PET Solved Paper-2005

  • question_answer
    The value of\[\int_{-\pi /2}^{\pi /2}{\log \left( \frac{2-\sin \theta }{2+\sin \theta } \right)dx}\]is

    A)  0                   

    B)  1

    C)  2                

    D)  None of these

    Correct Answer: A

    Solution :

     Let \[I=\int_{-\pi /2}^{\pi /2}{\log \left( \frac{2-\sin \theta }{2+\sin \theta } \right)}d\theta \] put \[\theta =-\theta \] \[I=\int_{-\pi /2}^{\pi /2}{\log \left( \frac{2-\sin (-\theta )}{2+\sin (-\theta )} \right)}\,d\theta \] \[=\int_{-\pi /2}^{\pi /2}{\log \left( \frac{2+\sin \theta }{2-\sin \theta } \right)}\,d\theta \] \[=\int_{-\pi /2}^{\pi /2}{-\log \left( \frac{2-\sin \theta }{2+\sin \theta } \right)}\,d\theta \] \[=-I\] \[\therefore \] \[I=0\]


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