垂直问题在立体几何中占有重要的地位,是历年高考命题的热点.空间中的垂直关系有:线线垂直、线面垂直、面面垂直,其中线线垂直是最基本、最主要的.它在三者转化过程中起着穿针引线的作用,证明线线垂直是解决垂直问题的关键,因此把证明线线垂直的方法研究透彻具有重要的意义. Vertical problems occupy an important position in the three-dimensional geometry, is the hot topic of the college entrance examination proposition over the years.Vertical relations in space are: line vertical, line vertical, face vertical, of which line vertical is the most basic, the most important. It plays a role of pin threading in the transformation of the three. It proves that line vertical is the key to solve the vertical problem. Therefore, it is of great significance to study the method of proving the line vertical.