One root of the equation $\cos x - x + \frac{1}{2} = 0$ lies in the interval

  • A

    $\left[ {0,\,\frac{\pi }{2}} \right]$

  • B

    $\left[ { - \frac{\pi }{2},\,0} \right]$

  • C

    $\left[ {\frac{\pi }{2},\,\pi } \right]$

  • D

    $\left[ {\pi ,\frac{{3\pi }}{2}} \right]$

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  • [IIT 1988]

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