辅助线是几何解题中沟通未知与已知的桥梁,是几何解题的难点所在,也是几何解题成败的关键.“新课程标准”降低了对几何解题中辅助线教学的要求,然而它却更加突出了以能力立意的数学思想方法,这样辅助线就成为解答难度较高的几何题目时无法回避的问题,那么几何解题中如何构造辅助线才能使问题得以顺利解决呢?请看下例. Auxiliary line is a bridge of unknown and known communication in geometric problem solving. It is the difficult point of geometric problem solving and the key to the success or failure of geometric solution. “New Course Standard” reduces the requirement for auxiliary line teaching in geometric problem solving. However, it highlights the ability to develop mathematical thinking methods. This way, the auxiliary line becomes an inescapable problem when solving difficult geometric problems. How can we construct the auxiliary line in the geometric problem solving so that the problem can be solved smoothly? Please see the following example.