JEE Main & Advanced Mathematics Inverse Trigonometric Functions Question Bank Critical Thinking

  • question_answer
    The equation \[{{\sin }^{-1}}x-{{\cos }^{-1}}x={{\cos }^{-1}}\left( \frac{\sqrt{3}}{2} \right)\]has

    A) No solution

    B) Unique solution

    C) Infinite number of solutions

    D) None of these

    Correct Answer: B

    Solution :

      We have \[{{\sin }^{-1}}x-{{\cos }^{-1}}x={{\cos }^{-1}}\frac{\sqrt{3}}{2}=\frac{\pi }{6}\] But \[{{\sin }^{-1}}x+{{\cos }^{-1}}x=\frac{\pi }{2}\] \ \[{{\sin }^{-1}}x=\frac{\pi }{3}\]and \[{{\cos }^{-1}}x=\frac{\pi }{6}\] Þ \[x=\frac{\sqrt{3}}{2}\]is the unique solution.


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