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

  • question_answer
    The set of values of k for which \[{{x}^{2}}-kx+{{\sin }^{-1}}(sin4)>0\] for all real x is

    A) \[\phi \]

    B) \[(-2,2)\]

    C) \[R\]

    D) \[(-\infty ,-2)\cup (2,\infty )\]

    Correct Answer: A

    Solution :

    [a] \[\because \frac{\pi }{2}<4<\frac{3\pi }{2},\] so \[{{\sin }^{-1}}\sin 4\] \[={{\sin }^{-1}}\sin (\pi -4)=\pi -4\] The inequality becomes \[{{x}^{2}}-kx+\pi -4>0\] The discriminant \[D={{k}^{2}}-4(\pi -4)>0\] for all k, That is \[{{x}^{2}}-kx+(\pi -4)>0\] cannot hold for all x.


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