KVPY Sample Paper KVPY Stream-SX Model Paper-22

  • question_answer
    \[\frac{\tan 2\alpha +\tan 3\alpha -\tan 5\alpha }{\tan 2\alpha .\tan 3\alpha .\tan 5\alpha }=?\]

    A) \[\tan \alpha \]

    B) \[\cot \alpha \]

    C) \[-1\]

    D)  1

    Correct Answer: C

    Solution :

    \[5\alpha =2\alpha +3\alpha \]
    take tangent both side
    \[\Rightarrow \]\[\tan 5\,\alpha =\frac{\tan 2\,\alpha +\tan 3\,\alpha }{1-\tan 2\,\alpha \tan 3\,\alpha }\]\[\Rightarrow \]\[\tan 5\,\alpha -\tan 2\alpha \cdot \tan 3\alpha \cdot \tan 5\alpha \]\[=\tan 2\alpha +\tan 3\alpha \]
    \[\therefore \]      \[-1=\frac{\tan 2\alpha +\tan 3\alpha -\tan 5\,\alpha }{tan2\alpha \cdot \tan 3\alpha \cdot \tan 5\,\alpha }\]
    \[\therefore \]      Ans. is C


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