转化思想是一种重要的思想,可以说,数学解题的过程就是不断由陌生向熟悉,由未知向已知,由难到易的转化过程.我们学习的平行线的判定定理,就包含两个方面的转化:(1)课本通过三角尺的平移得出:只要保持同位角相等,画出的直线就平行于已知直线,从而引出了平行线的判定方法:同位角相等,两直线平行.然后通过推理,得出内错角相等,两直线平行;同旁内角互补,两直线平行.这实际上是通过将内错角和同旁内角的关系转 Conversion thinking is an important idea, it can be said that the process of mathematical problem solving is constantly unfamiliar to the familiar, from unknown to known, difficult to easy conversion process.We study the parallel lines of the decision theorem, including two (1) The translation of the textbook through the trigonometric rule leads to that: as long as the same orientation angle is maintained, the drawn line is parallel to the known straight line, thus leading to the method of determining parallel lines: the same phase angle and the two straight lines are parallel Then, through reasoning, it is concluded that the internal error angles are equal and the two straight lines are parallel, and that the internal angles of the two adjacent lines are complementary to each other and that the two straight lines are parallel to each other.