9. Given the complex number $z=\cos \alpha+\mathrm{i}(1-\sin \alpha), \alpha \in\left(\frac{\pi}{2}, 2 \pi\right)$. If $w=z^{2}-2 \mathrm{i} z$, then the trajectory of the point corresponding to $w$ on the complex plane is $\qquad$ .
9. A circle with center at $(1,0)$ and radius 1.