JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Fundamental Integration

  • question_answer
    \[\int_{{}}^{{}}{\frac{1}{\sqrt{1+\cos x}}\ dx=}\]

    A)            \[\sqrt{2}\log \left( \sec \frac{x}{2}+\tan \frac{x}{2} \right)+K\]            

    B)            \[\frac{1}{\sqrt{2}}\log \left( \sec \frac{x}{2}+\tan \frac{x}{2} \right)+K\]

    C)            \[\log \left( \sec \frac{x}{2}+\tan \frac{x}{2} \right)+K\]           

    D)            None of these

    Correct Answer: A

    Solution :

               \[\int_{{}}^{{}}{\frac{1}{\sqrt{1+\cos x}}}\,dx=\int_{{}}^{{}}{\frac{dx}{\sqrt{2{{\cos }^{2}}(x/2)}}}=\frac{1}{\sqrt{2}}\int_{{}}^{{}}{\sec \frac{x}{2}\,dx}\]            \[=\frac{1}{\sqrt{2}}\left\{ \log \left( \sec \frac{x}{2}+\tan \frac{x}{2} \right) \right\}.\frac{1}{1/2}=\sqrt{2}\log \left( \sec \frac{x}{2}+\tan \frac{x}{2} \right)+K\].


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