Find the divergence of the vector field $\vec F = \vec a\times \vec r$, if $\vec r = x\,\mathit{\vec i}+y\,\mathit{\vec j}+z\,\mathit{\vec k}$ and $\vec a = 2\,\mathit{\vec i}+6\,\mathit{\vec j}+2\,\mathit{\vec k}$, by first calculating the cross-product.

$\vec F =$
so that $\mbox{div }\vec F =$