JEE Main & Advanced Mathematics Inverse Trigonometric Functions Question Bank Self Evaluation Test - Inverse Trigonometric Functions

  • question_answer
    If \[u={{\cot }^{-1}}\sqrt{\tan \alpha }-{{\tan }^{-1}}\sqrt{\tan \alpha },\] then  \[\tan \left( \frac{\pi }{4}-\frac{u}{2} \right)\] is equal to

    A) \[\sqrt{\tan \alpha }\]

    B) \[\sqrt{\cot \alpha }\]

    C) \[\tan \alpha \]

    D) \[\cot \alpha \]

    Correct Answer: A

    Solution :

    [a] Let \[\sqrt{\tan \alpha }=\tan x,\] Then \[u={{\cot }^{-1}}(tanx)-ta{{n}^{-1}}(tanx)\] \[=\frac{\pi }{2}-x-x=\frac{\pi }{2}-2x\] \[\Rightarrow 2x=\frac{\pi }{2}-u\Rightarrow x=\frac{\pi }{4}-\frac{u}{2}\] \[\Rightarrow \tan x=\tan \left( \frac{\pi }{4}-\frac{u}{2} \right)\Rightarrow \sqrt{\tan \alpha }=\tan \left( \frac{\pi }{4}-\frac{u}{2} \right)\]


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