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

  • question_answer
    \[\int_{0}^{\pi /4}{{{\sec }^{7}}\theta {{\sin }^{3}}\theta }\,d\theta =\]

    A)                 \[\frac{1}{12}\]

    B)                 \[\frac{3}{12}\]

    C)                 \[\frac{5}{12}\]

    D)                 None of these

    Correct Answer: C

    Solution :

               \[\int_{0}^{\pi /4}{{{\sec }^{7}}\theta }.{{\sin }^{3}}\theta \,d\theta \]=\[\int_{0}^{\pi /4}{\frac{{{\sin }^{3}}\theta }{{{\cos }^{3}}\theta }.{{\sec }^{4}}\theta \,d\theta }\]                    Putting \[\tan \theta =t,\] it reduces to                                 \[\int_{0}^{1}{{{t}^{3}}(1+{{t}^{2}})\,dt}\]= \[\left| \frac{{{t}^{4}}}{4}+\frac{{{t}^{6}}}{6} \right|_{0}^{1}=\frac{5}{12}\].


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