在证明两个三角形相似时,常常会出现证两次相似,而第一次相似常由两角相等证得,第二次相似常由第一次相似所得的比例线段进行适当变化再加上夹角相等而证得,可归纳成:两角相等,三角形相似,比例线段,新的比例线段+夹角相等,新的三角形相似. In the proof that the two triangles are similar, there is often evidence that the two times are similar, and the first similarity is often proved by two equal angles, and the second similarity is often changed by the first similarly derived proportional line plus the clip. The angles are equal and they can be summarized as: two angles are equal, triangles are similar, scale lines, new scale lines + angles are equal, new triangles are similar.