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

  • question_answer
    Let \[-1\le x\le 1.\] If \[\cos (si{{n}^{-1}}x)=\frac{1}{2},\] then how many value does \[\tan (co{{s}^{-1}}x)\] assume?

    A) One

    B) Two

    C) Four     

    D) Infinite

    Correct Answer: B

    Solution :

    [b] As given : \[\cos \left( {{\sin }^{-1}}x \right)=\frac{1}{2}\] \[\Rightarrow {{\sin }^{-1}}x={{\cos }^{-1}}\left( \frac{1}{2} \right)\] \[\Rightarrow x=\sin \frac{\pi }{3}=\frac{\sqrt{3}}{2}\] \[\therefore \tan (co{{s}^{-1}}x)=tan\left( {{\cos }^{-1}}\frac{\sqrt{3}}{2} \right)\] \[=\tan \left( \pm \frac{\pi }{6} \right)=\pm \frac{1}{\sqrt{3}}\] Hence, \[\tan (co{{s}^{-1}}x)\] have two values.


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