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笔者在使用人教版数学九年级(下)教材及教参教学第二十七章《相似》的过程中,遇到了几道让人揪心的课本习题,在学习过程中师生们有明显的不同看法,存在疑惑,特在此提出来与各位同行和专家交流、讨论.教材第53页练习第4小题:在一张复印出来的纸上,一个多边形的一条边由原图中的2cm变成了6cm,这次复印的放缩比例是多少?这个多边形的面积发生了怎样的变化?教参上给出的答案是:放缩比例是3,面积扩大到
In the process of using the PEP (mathematics ninth grade) (the second) textbook and teaching reference (Chapter 27) “similar”, the author encountered several worrying textbook exercises. During the learning process, the teachers and students had obvious Different views, there are doubts, especially in this proposed to exchange and discuss with your colleagues and experts.Teaching materials 第 53 页 Practice fourth small topic: On a copy of the paper out of a polygon side from the original 2cm Into a 6cm, what is the scaling ratio of this copy? What happens to the area of the polygon? The answer given in the tutorial is that the scaling ratio is 3, the area is expanded to