The voronoi flower of a compact set $F\subseteq\mathbb{R}^d$ with respect to a point $x$ is given by $$\mathcal{F}_x(F):=\bigcup_{y\in F}B_{\|y-x\|}(y).$$
I need to show that $\mathcal{F}_x(F)=\mathcal{F}_x(\text{conv}(F))$. This is a result that is generally known, but I haven't been able to find a proof of it.
So far, I've tried to prove it directly. For $F=\{a,b\}$ and $y=\alpha a+(1-\alpha)b$. Assuming $\|y-z\|<\|y-x\|$ and $\|a-z\|>\|a-x\|$ to show that $\|b-z\|<\|b-x\|$, but when I try to apply the triangle inequality I can't get there.