11. In the Cartesian coordinate system: there are four points $A(-8,3)$, $B(-4,5)$, $C(0, n)$, $D(m, 0)$. When the perimeter of quadrilateral $ABCD$ is minimized, the value of $\frac{m}{n}$ is -. $\qquad$
11. $-\frac{3}{2}$