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

  • question_answer
    \[\int_{0}^{\pi /2}{\frac{\sin x\cos x}{1+{{\sin }^{4}}x}\,dx=}\]                                   [AISSE 1988]

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

    B)                 \[\frac{\pi }{4}\]

    C)                 \[\frac{\pi }{6}\]              

    D)                 \[\frac{\pi }{8}\]

    Correct Answer: D

    Solution :

               Put \[{{\sin }^{2}}x=t\Rightarrow dt=2\sin x\cos x\,dx\]                       Now\[\int_{0}^{\pi /2}{\frac{\sin x\cos x}{1+{{\sin }^{4}}x}dx=\frac{1}{2}\int_{0}^{1}{\frac{1}{1+{{t}^{2}}}dt=\frac{1}{2}[{{\tan }^{-1}}t]_{0}^{1}=\frac{\pi }{8}}}\].


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