几个关于极坐标的Bonnesen型不等式
SEVERAL BONNESEN-STYLE INEQUALITIES ABOUT POLAR COORDINATES

本文研究了平面上C2闭凸曲线的极坐标形式{O；ρ（θ）}.运用Bonnesen不等式的推广形式[1，2]，得到关于ρ及ρθ的一些积分形式的Bonnesen型不等式，使得我们很容易得到等周不等式取等时的条件.
In this paper, we study C2 convex closed plane curve inpolar coordinates {O; ρ(θ)}. By using the extended Bonnesen inequalities [1, 2], we obtain some new Bonnesen-type inequalities about integration of ρ and ρθ, so that we can easily get the conditions under which equality in the isoperimetric inequality holds