等积式的证明方法一般有两种,第一种方法是直接证明三角形相似(或全等),然后由对应边成比例(或相等),即可得证.本文重点介绍证明等积式的另一种方法——等量代换.这种方法的基本思路也是证明三角形相似,但是要把其中的一些量进行替换.相信下面的例子能使同学们有所启发. There are two general proof methods for the isomorphic method. The first method is to directly prove that the triangles are similar (or congruent) and then proportional (or equal) are obtained from the corresponding edges. This paper focuses on the proof of isomorphism. Another method - equal substitution. The basic idea of ​​this method is also to prove that triangles are similar, but some of them need to be replaced. I believe the following examples can make students inspire.