人教版《数学》九年级(上册)第22页《阅读与思考》中介绍了海伦一秦九韶公式,但文中并未给出公式的证明;我们在给学生介绍这个公式时,不少学生对公式的证明产生了兴趣,课上他们有的在沉思,有的忙于纸上演算,有的几人凑在一起讨论……,这是我们在备课中没有预想到的情况;现在学生还没有具备三角函数、正(余)弦定理等知识,学生现有知识能否证明这个 People's Education Edition “Mathematics” ninth grade (Volume) page 22 “Reading and Thinking,” introduced a Helen-Qin Jiu Shao formula, but the paper did not give the formula to prove that when we introduce students to this formula, many students Proof of formula has generated interest in some of them meditating on the class, and some are busy on paper calculus, and some people together to discuss ... ... This is what we did not expect in lesson preparation; now students do not have Trigonometric function, positive (residual) string theorem and other knowledge, students can prove this knowledge