a
\(\,\mathop v\limits^ \to \,\, = \,\,\mathop \omega \limits^ \to \,\, \times \,\,\mathop r\limits^ \to \,\, = \,\,\left| {\left. {\,\begin{array}{*{20}{c}}
{\hat i}&{\hat j}&{\hat k}\\
1&{ - 2}&3\\
1&1&1
\end{array}\,} \right|} \right.\,\, = \,\, - 5\hat i\,\, + \;\;2\hat j\,\, + \;\,3\hat k\)