三、关于巧添辅助线和辅助面由于在空间中研究问题总不如在平面上研究问题来得简单方便,因此,在研究立体几何问题时常想办法将平面与平面的位置关系问题转化成直线和平面的位置关系问题,进而再转化成直线和直线的位置关系问题(这种处理问题的方法叫“降维法”)。 Third, on the addition of auxiliary lines and auxiliary surfaces Because the research problem in the space is not as simple as studying the problems on the plane, therefore, when studying the three-dimensional geometry, we often think of ways to transform the positional relationship between planes and planes into straight lines and planes. The problem of positional relationships, in turn, translates into the problem of positional relationships between straight lines and straight lines (this method of dealing with problems is called the “dimensional dimension reduction method”).