\( = \left| {\,\begin{array}{*{20}{c}}{\hat i\,\,}&{\hat j\,\,}&{\hat k}\\{3\,\,}&{1\,\,}&2\\{2\,\,\,}&{ - 2\,\,\,}&4\end{array}\,} \right|\, \)
\(=(1 \times 4 - 2 \times - 2)\hat i + (2 \times 2 - 4 \times 3)\hat j + (3 \times - 2 - 1 \times 2)\hat k\) \( = 8\hat i - 8\hat j - 8\hat k\)
\(\overrightarrow {\rm{A}} \, \times \overrightarrow {\rm{B}} \, = \,|\overrightarrow {\rm{A}} \times \overrightarrow {\rm{B}} |\, = \sqrt {{{(8)}^2} + {{( - 8)}^2} + {{( - 8)}^2}} \,\) \( = 8\sqrt 3 \)