Find the angle between the vectors $2\hat i\;-\hat j\;-\hat k$ and $3\hat i\;+4\hat j\;+\hat k$.

Question

$\begin{array}{1 1} cos^{-1} \bigg(\large \frac{1}{\sqrt{156}} \bigg) \\ cos^{-1} \bigg(\large \frac{9}{\sqrt{156}} \bigg) \\ cos^{-1} \bigg(\large \frac{11}{\sqrt{156}} \bigg) \\ cos^{-1} \bigg(\large \frac{3}{\sqrt{156}} \bigg) \end{array} $