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《中小学数学》(初中版)连续刊登了贵刊编者撰写的《几何学中的空间与图形》一文,阅后受益不浅.但在2012年第四期刊登的文章中,笔者发现了一个值得商榷的问题.我们来看看原文:几何中有两个定理是尤其值得学习和掌握的,一个是欧几里得《几何原本》中的命题Ⅲ.20:“在一个圆中,同一弧对应的圆心角是圆周角的两倍.”这个定理有两个推论:(1)在同一圆中,同一条弦所对的所有圆周角都相等;
“Primary and secondary mathematics” (junior high school version) published a series of articles published in your editor’s compilation of “space and graphics in geometry,” a lot of benefit after reading.But in the fourth issue of 2012 article, I found a A question worth discussing: Let us look at the original text: There are two theorems in geometry that are especially worth learning and mastery. One is the proposition III.1 in Euclidean Geometry Original: “In a circle, the same The center angle of the arc corresponds to twice the circumference angle. ”" There are two corollaries to this theorem: (1) In the same circle, all the circumference angles for the same string are equal;