JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    If\[\tan (\cot x)=\cot (\tan x)\], then\[\sin 2x\]is equal to

    A) \[\frac{2}{(2n+1)\pi }\]                 

    B) \[\frac{2}{(2n+1)\pi }\]

    C) \[\frac{2}{n(n+1)\pi }\]                 

    D) \[\frac{4}{n(n+1)\pi }\]

    Correct Answer: B

    Solution :

    Given,\[\tan (\cot x)=\cot (\tan x)\]                                 \[=\tan \left( \frac{\pi }{2}-\tan x \right)\] \[\Rightarrow \]               \[\cot x=n\pi +\left( \frac{\pi }{2}-\tan x \right)\] \[\Rightarrow \]               \[\cot x+\tan x=n\pi +\frac{\pi }{2}\] \[\therefore \]  \[\frac{1}{\sin x\cos x}=\frac{\pi }{2}(2n+1)\] \[\Rightarrow \]               \[\sin 2x=\frac{4}{(2n+1)\pi }\]


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