与圆有关的问题、概念和定理较多,知识面广,综合性强,而题中已知条件较分散,不易直接应用定理,常需添加适当的辅助线,使其起到沟通条件与结论间的联系的纽带作用.现介绍常用的辅助线添法,以掌握其一般规律,使解题正确,快捷. There are many problems, concepts, and theorems related to circles, knowledge is wide, and comprehensiveness is strong. The known conditions in the questions are scattered and it is not easy to directly apply the theorems. It is often necessary to add appropriate auxiliary lines to make them communicate conditions and conclusions. The link between the links. Now introduce the commonly used auxiliary line method, in order to grasp its general rules, so that the correct solution, fast.