A Delaunay triangulation for a set $P$ of points in a plane is a triangulation $DT(P)$ such that no point in $P$ is inside the circumcircle of any triangle in $DT(P)$.
A Voronoi diagram is a partitioning of a plane into regions based on distance to points (called sites) in a specific subset of the plane.
We know that Delaunay triangulation is the dual of Voronoi diagram.
How can we prove that the boundary of Delaunay Triangulation is the convex hull of sites?