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对于通用教材高中数学第二册复习题五第28题,笔者根据它的特点,试着用几种方法进行分析,使学生能从不同的角度得出正确的结论,从而提高学生分析问题的能力,现在把我的做法写在下面,和大家一起探讨,不妥之处望批评指正。第28题是,如图,将正方体的棱分为四等分,在1/4处截去各棱角,得到一个多面体,正方体的体积减少了几分之几? 如何理解“在1/4处截去各棱角”是解此题的关键,换句话,就是怎样将正方体切割成如图的多面体(即多面体是怎样形成的)为了把这一点给学生讲清楚,可用粗铁丝作一个正方体的骨架模型,然后用三
For the twenty-eighth question in the second-year review book of general mathematics mathematics high school mathematics, according to its characteristics, the author tried to use several methods for analysis, so that students can draw correct conclusions from different perspectives, thereby improving students’ ability to analyze problems. Now write down my practice below and discuss it with everyone. The 28th question is, as shown in the figure, divide the cube of the cube into four equal parts, and cut off the edges and corners at 1/4 to obtain a polyhedron. The volume of the cube is reduced by a few fractions. How to understand “at 1/4 The key to solving this problem is to cut off the edges and corners. In other words, how to cut the cube into the polyhedron of the figure (ie, how the polyhedron is formed). In order to make this clear to the students, a thick rectangular wire can be used as a cube. Skeleton model, then use three