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1问题提出题目:如图1,求∠A+∠B+∠C+∠D+∠E+∠F+∠G的度数。某QQ群中发布一条信息:上述题目,你会怎么引导学生寻找解题思路?各种解题思路的共性是什么?现将笔者对本题的一些思考整理成文,与大家分享。2问题分析从题目本身看,图形就是已知条件,而要求的是图形各“角”的度数之和;从图形外围看,它是由一些“8字形”的连贯三角形“堆成”的;从图形内部看,它是一个凸多边形;从外围三角形的个数与内部凸多边形的边数两者间的数量关系来看,它们是相等的。本
1 questions raised the subject: Figure 1, seeking ∠ A + ∠ B + ∠ C + ∠ D + ∠ E + ∠ F + ∠ G degree. A QQ group posted a message: The above topics, how do you guide students to find ways to solve the problem? What is the common problem solving ideas? Now the author of some of the questions on this issue finishing, and share with you. 2 Problem Analysis From the point of view of itself, the graph is a known condition, and the requirement is the sum of the degrees of the graph. From the periphery of the graph, it is composed of some coherent triangles " It is a convex polygon when viewed from the interior of the figure; they are equal from the quantitative relationship between the number of peripheral triangles and the number of convex polygons inside. this