圆有关的线段数量关系探究问题在近年来中考中屡见不鲜.解答它们,除了灵活利用圆的有关性质外,有时还要注意考虑借三角形全等之力,或借勾股定理之力,或借三角形相似之力.现举例如下:例1(2015年山东省德州市)如图1,A、P、B、C是⊙O上的四个点,∠APC=∠CPB=60°. Circles related to the relationship between the number of segments in recent years in the examination in the common. Answer them, in addition to flexible use of the relevant nature of the circle, and sometimes also pay attention to consider by the power of the triangle congruent, or by the Pythagorean theorem, or by the triangle For example: Example 1 (Dezhou, Shandong Province, 2015) As shown in Figure 1, A, P, B and C are four points on ⊙O, ∠APC = ∠CPB = 60 °.