JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Fundamental Integration

  • question_answer
    \[\int_{{}}^{{}}{\frac{\cos x-1}{\cos x+1}\ dx=}\]       [MP PET 1989, 92]

    A)            \[2\tan \frac{x}{2}-x+c\]

    B)            \[\frac{1}{2}\tan \frac{x}{2}-x+c\]

    C)            \[x-\frac{1}{2}\tan \frac{x}{2}+c\]

    D)            \[x-2\tan \frac{x}{2}+c\]

    Correct Answer: D

    Solution :

               \[\int_{{}}^{{}}{\frac{\cos x-1}{\cos x+1}\,dx=-\int_{{}}^{{}}{{{\tan }^{2}}\frac{x}{2}\,dx}}\]            \[=-\int{\left( {{\sec }^{2}}\frac{x}{2}-1 \right)\,dx}=\int{\left( 1-{{\sec }^{2}}\frac{x}{2} \right)dx=x-2\tan \frac{x}{2}+c}\].


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