解决与圆有关的几何问题时,常常需要添加适当的辅助线将复杂的图形转化为基本图形,从而方便求解.为了帮助同学们正确理解并掌握圆中有关计算题或证明题的一般解法,现就圆中辅助线的常规作法分类例析如下.一、圆中有弦,常作弦心距,或者作垂直于弦的半径或直径,有时还要连接过弦端点的半径. To solve the circle-related geometric problems, often need to add the appropriate auxiliary line will be complex graphics into basic graphics, so as to facilitate the solution.In order to help students to correctly understand and grasp the circular calculation or proof questions on the general solution, now A typical example of an auxiliary line in the circle is as follows: 1. A chord in the circle, often used as a chord center, or a radius or diameter perpendicular to the chord, and sometimes also the radius of the end point of the chord.