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

  • question_answer
    If \[{{\sin }^{-1}}\left( \frac{2a}{1+{{a}^{2}}} \right)-{{\cos }^{-1}}\left( \frac{1-{{b}^{2}}}{1+{{b}^{2}}} \right)={{\tan }^{-1}}\left( \frac{2x}{1-{{x}^{2}}} \right),\]then what is the value of x?

    A) \[a/b\]

    B) \[ab\]

    C) \[b/a\]  

    D) \[\frac{a-b}{1+ab}\]

    Correct Answer: D

    Solution :

    [d] Given, \[{{\sin }^{-1}}\left( \frac{2a}{1+{{a}^{2}}} \right)-{{\cos }^{-1}}\left( \frac{1-{{b}^{2}}}{1+{{b}^{2}}} \right)=ta{{b}^{-1}}\left( \frac{2x}{1-{{x}^{2}}} \right)\] \[\therefore 2{{\tan }^{-1}}a-2{{\tan }^{-1}}b=2{{\tan }^{-1}}x\] \[\Rightarrow {{\tan }^{-1}}a-{{\tan }^{-1}}b={{\tan }^{-1}}x\] \[\Rightarrow {{\tan }^{-1}}\left( \frac{a-b}{1+ab} \right)={{\tan }^{-1}}x\] \[\Rightarrow x=\frac{a-b}{1+ab}\]


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