本文所提的基本图形是指两条平行线被第三条直线所截的基本图形,即图l(以下同).本文所指的定理是指:如果一个角的两边分别平行于另一个角的两边,那么这两个角相等或互补(以下同).从基本图形中引出定理,就是从知识之间的内在联系入手,引导学生将基本图形中的各对同位角、内错角、同旁内角平移出来,然后引导学生对上述操作进行反思、接着 The basic figure mentioned in this paper refers to the basic figure that two parallel lines are truncated by a third straight line, that is Figure 1 (below). The theorem in this paper refers to: If two sides of one corner are parallel to the other On both sides, then the two angles are equal or complementary (hereinafter the same). The theorem drawn from the basic graph is to start with the internal connection between the knowledge and guide the students in the basic graph of the various pairs of azimuth angle, the inner angle, the same The lateral angles are shifted out and guide the students to reflect on the above operations, and then