Before revision:  In this paper, we prove that \theta\leq 2\pi-2\pi{r.m} such that m and r are the number of edges and internal points of CH , respectively.
After revision:  In this paper, we prove that \theta\leq 2\pi-2\pi{r.m} such that m and r are the number of edges and inner points of the convex hull of S , respectively.