在拙文 [1 ]中 ,我们定义了圆外切闭折线的“ｋ号界心”概念 ,并揭示了它的一些有趣性质。这里作点补充。为此 ,先介绍如下概念 :定义 1　在△ＯＡＢ所在的平面内 ,以顶点Ｏ为原点建立直角坐标系ｘＯｙ ,设顶点Ａ和Ｂ的坐标分别为(ｘＡ,ｙＡ)、(ｘＢ,ｙＢ) ,那么式子 (ｘＡｙＢ In Yi Wen [1], we defined the notion of “k-boundary” for the outer cut-off polyline, and revealed some of its interesting properties. Here’s something to add. To this end, first introduce the following concepts: Definition 1 In the plane where △ OAB is located, establish a rectangular coordinate system xOy with vertex O as the origin, and set the coordinates of vertex A and B as (xA, yA), (xB, yB), respectively. Then the formula (xAyB