JEE Main & Advanced Mathematics Inverse Trigonometric Functions Question Bank Inverse trigonometric functions

  • question_answer
    If \[{{\cot }^{-1}}\alpha +{{\cot }^{-1}}\beta ={{\cot }^{-1}}x,\]then \[x=\] [MP PET 1992]

    A) \[\alpha +\beta \]

    B) \[\alpha -\beta \]

    C) \[\frac{1+\alpha \beta }{\alpha +\beta }\]

    D) \[\frac{\alpha \beta -1}{\alpha +\beta }\]

    Correct Answer: D

    Solution :

    Given that \[{{\cot }^{-1}}\alpha +{{\cot }^{-1}}\beta ={{\cot }^{-1}}x\] \[\Rightarrow {{\cot }^{-1}}\left( \frac{\alpha \beta -1}{\alpha +\beta } \right)={{\cot }^{-1}}x\Rightarrow x=\frac{\alpha \beta -1}{\alpha +\beta }\].


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