在研读了《中小学数学》初中版2010年7—8期邵晓芳的《“陷阱”背后的陷阱》一文后,颇有感触,深受启发,对这个问题进行了再思考,感到这样的问题其实是可以避免的.现整理如下,希望各位同行指正.先看射影定理:如图1,Rt△ABC中,已知∠ACB=90°,CD⊥AB,可得AC~2=AD·AB,BC~2=BD·AB,CD~2=AD·BD三个等式.其实对其中的前两个等式在一般的三角 After reading the article entitled “Junior high school mathematics” junior high school version 2010-7-8 Shao Xiaofang “” trap “behind the trap ” article, quite touching, inspired by, rethinking on this issue, feel this The problem is actually avoided. Now collated as follows, I hope you correct colleagues. First look projective theorem: Figure 1, Rt △ ABC, known ∠ ACB = 90 °, CD ⊥ AB, available AC ~ 2 = AD · AB, BC ~ 2 = BD · AB, CD ~ 2 = AD · BD three equations. In fact, the first two of them in the general triangle