CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    If\[y={{\cot }^{-1}}\left( \tan \frac{x}{2} \right),\]then\[\frac{dy}{dx}\] is equal to

    A)  \[\frac{1}{2}\]                                  

    B)  \[0\]                    

    C)  \[\frac{x}{2}\]                  

    D)         \[-\frac{1}{2}\]

    E)  \[-\frac{x}{2}\]

    Correct Answer: D

    Solution :

    \[y={{\cot }^{-1}}\left( \tan \frac{x}{2} \right)\] \[y={{\cot }^{-1}}\cot \left( \frac{\pi }{2}-\frac{x}{2} \right)\] \[y=\frac{\pi }{2}-\frac{x}{2}\]    Differentiating w.r.t.\[x\]on both sides,                 \[\frac{dy}{dx}=-\frac{1}{2}\]                    


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