近几年来 ,全国初中数学竞赛题中有几道几何题 ,似乎与圆无关 ,但借助辅助圆求解 ,却能事半功倍 ,本文特举例说明 ,供参考 .例 1　如图 1,在△ＡＢＣ中 ,∠ＡＢＣ =60° ,点Ｐ是△ＡＢＣ内的一点 ,使得∠ＡＰＢ=∠ＢＰＣ =∠ＣＰＡ ,且ＰＡ =8,ＰＣ =6则ＰＢ = .(2 0 0 2年全国 In recent years, there are several geometric questions in the national junior high school math contest. It seems that it has nothing to do with the circle, but it can be done more efficiently with the help of the auxiliary circle. This article gives an example for illustration. Example 1 As shown in Figure 1, in △ABC, ∠ABC =60°, point P is a point within △ABC, such that ∠APB=∠BPC =∠CPA, and PA =8, and PC =6 then PB = .(2nd