J & K CET Engineering J and K - CET Engineering Solved Paper-2007

  • question_answer
    \[\int{\frac{1}{1+\cos \,\,ax}}\,\,dx\] is equal to

    A)  \[\cot \,\frac{ax}{2}+c\]

    B)  \[\frac{1}{a}\,\tan \,\frac{ax}{2}+c\]

    C)  \[\frac{1}{a}(\text{cosec ax - cot ax)+c}\]

    D)  \[\frac{1}{a}(\text{cosec ax + cot ax)+c}\]

    Correct Answer: B

    Solution :

    \[\int{\frac{1}{1+\cos \,ax}}\,dx\] \[=\int{\frac{dx}{2\,{{\cos }^{2}}\,(ax/2)}}\] \[=\frac{1}{2}\int{{{\sec }^{2}}\,\frac{ax}{2}\,dx=\frac{1}{2}}.\frac{\tan ax/2}{a/2}\] \[=\frac{1}{a}\tan \frac{ax}{2}+c\]


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