判定两直线异面的依据是什么 ?是异面直线的定义 .异面直线的定义是 :“不同在任何一个平面内的两条直线叫做异面直线” .要对任何一个平面进行检验 ,这是不可能的 ,因此 ,用异面直线的定义时 ,必须用到反证法 .请看课本中的一道例题 :过平面外一点与平面内一点的直线 ,和平面 What is the basis for determining the difference between two straight lines? The definition of a straight line with different sides. The definition of a straight line with different sides is: “The two straight lines that are different in any plane are called straight lines with different sides”. To test any plane, this It is impossible, therefore, to use the definition of a non-planar straight line, the anti-evidence method must be used. Look at an example in the textbook: crossing a point outside the plane and a point inside the plane, and the plane