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

  • question_answer
    If \[4{{\sin }^{-1}}x+{{\cos }^{-1}}x=\pi ,\]then\[x\]is equal to  [UPSEAT 2001]

    A) 0

    B) \[\frac{1}{2}\]

    C) \[-\frac{\sqrt{3}}{2}\]

    D) \[\frac{1}{\sqrt{2}}\]

    Correct Answer: B

    Solution :

     We know that \[4{{\sin }^{-1}}x+{{\cos }^{-1}}x=\pi \] Þ \[3{{\sin }^{-1}}x+{{\sin }^{-1}}x+{{\cos }^{-1}}x=\pi \] Þ \[3{{\sin }^{-1}}x=\pi -\frac{\pi }{2}=\frac{\pi }{2}\] Þ \[{{\sin }^{-1}}x=\pi /6\]Þ  \[x=\sin \frac{\pi }{6}=\frac{1}{2}\].


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