有一类关于a2=bc和和a∶b=c∶d的几何题,虽然应用三点定位法能找到与结论有关的两个三角形,但是这两个三角形并不相似,因而使证明陷入困境.然而借助等量代换,却能柳暗花明,使结论很快得证.现举例如下,供初中师生教学参考.1等线代换 There is a class of geometry questions about a2 = bc and a: b = c: d. Although three triangles are used to find the two triangles that are relevant to the conclusion, the two triangles are not similar and therefore prove to be in trouble. However, with the same amount of substitution, it can be superficial, so that the conclusions soon proved. Now for example below, for junior high school teachers and students teaching reference .1 equal substitution