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

  • question_answer
    \[\int_{\,\pi /6}^{\,\pi /3}{\,\frac{dx}{1+\sqrt{\cot x}}}\] is                                           [DCE 2001]

    A)                 \[\pi /3\]             

    B)                 \[\pi /6\]

    C)                 \[\pi /12\]

    D)                 \[\pi /2\]

    Correct Answer: C

    Solution :

               \[I=\int_{\pi /6}^{\pi /3}{\frac{dx}{1+\sqrt{\cot x}}=}\int_{\pi /6}^{\pi /3}{\frac{\sqrt{\sin x}}{\sqrt{\sin x}+\sqrt{\cos x}}\,}dx\]   ?..(i)            \[I=\int_{\pi /6}^{\pi /3}{\frac{\sqrt{\cos x}}{\sqrt{\cos x}+\sqrt{\sin x}}\,}dx\]                       .....(ii)                 Adding (i) and (ii), \[2I=\int_{\,\pi /6}^{\,\pi /3}{dx}\]; \[I=\frac{1}{2}\left( \frac{\pi }{3}-\frac{\pi }{6} \right)=\frac{\pi }{12}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner