7. If the circle $x^{2}+y^{2}=r^{2}$ covers at least one maximum point and one minimum point of the function $f(x)=\sqrt{30} - \sin \frac{\pi x}{2 \sqrt{r}}$ (in this problem, if $x=x_{0}$, $f(x)$ reaches the maximum value $M$, then $\left(x_{0}, M\right)$ is called a maximum point; similarly for a minimum point), then the range of the positive number $r$ is
7. $[6,+\infty)$