d
\(\mathop \tau \limits^ \to \, = \,\,\mathop {\text{r}}\limits^ \to \,\, \times \,\,\mathop {\text{F}}\limits^ \to \,\, = \,\,\left| {\left. {\begin{array}{*{20}{c}}
{\hat i}&{\hat j}&{\hat k} \\
7&3&1 \\
2&1&4
\end{array}} \right|} \right.\,\, = \,\,11\hat i\,\, - \,\,26\hat j\,\, + \;\,\hat k\)