Find unit vector perpendicular to $\vec A$ and $\vec B$ where $\vec A = \hat i - 2\hat j + \hat k$ and $\vec B = \hat i + 2\hat j$

  • A

    $\frac{{2\hat i + \hat j + 4\hat k}}{{\sqrt {21} }}$

  • B

    $\frac{{ - 2\hat i + \hat j + 4\hat k}}{{\sqrt {21} }}$

  • C

    $\frac{{ - 2\hat i - \hat j + 4\hat k}}{{\sqrt {21} }}$

  • D

    $\frac{{2\hat i + \hat j + 4\hat k}}{{\sqrt 5 }}$

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