当两圆相交时,往往连结公共弦作为辅助线,将在两个圆中的角联系起来,以便利用圆的有关性质,将问题迅速解决.对此同学们务必要有深刻的印象. When the two circles intersect, they often connect the common string as an auxiliary line, linking the angles in the two circles so that the problem can be solved quickly by taking advantage of the relevant nature of the circle. The students must have a deep impression.