The routine returns the length of the diagonal of the given square Sq.

The command with(geometry,diagonal) allows the use of the abbreviated form of this command.

$\mathrm{with}\left(\mathrm{geometry}\right)\:$

$\mathrm{point}\left(A\,0\,0\right),\mathrm{point}\left(B\,1\,0\right),\mathrm{point}\left(C\,1\,1\right),\mathrm{point}\left(F\,0\,1\right)\:$

$\mathrm{square}\left(\mathrm{Sq}\,\left[A\,B\,C\,F\right]\right)$

$\mathrm{Sq}$

$\mathrm{diagonal}\left(\mathrm{Sq}\right)$

$\sqrt{2}$