JEE Main & Advanced Mathematics Definite Integration Question Bank Fundamental definite integration, Definite integration by substitution

  • question_answer
    \[\int_{0}^{2\pi }{{{e}^{x/2}}.\sin \left( \frac{x}{2}+\frac{\pi }{4} \right)\,dx=}\]                                 [Roorkee 1982]

    A)                 1             

    B)                 \[2\sqrt{2}\]

    C)                 0             

    D)                 None of these

    Correct Answer: C

    Solution :

               Let \[I=\int_{0}^{2\pi }{{{e}^{x/2}}\sin \left( \frac{x}{2}+\frac{\pi }{4} \right)\,dx}\]                    Þ \[I=2\int_{0}^{\pi }{{{e}^{t}}\sin \left( t+\frac{\pi }{4} \right)dt}=2\left[ \frac{{{e}^{t}}}{\sqrt{1+1}}\sin \left( t+\frac{\pi }{4}-{{\tan }^{-1}}\frac{1}{1} \right) \right]_{0}^{\pi }\]                               \[=\frac{2}{\sqrt{2}}\left[ {{e}^{t}}\sin t \right]_{0}^{\pi }=\frac{2}{\sqrt{2}}[0]=0\].


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