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学生在解答立体几何问题中暴露的诸多薄弱环节,突出表现为空间想象能力较差,空间概念模糊,从而导致计算、论证等方面的错误.本文根据平时常见错误加以剖析,仅供参考。一、概念不清例1.一个正方体A1B1C1D1-ABCD的棱长为a。(1)过它的上底两邻边A1D1、D1C1的中点E1、F1和下底的中心O作一个截面,求这个截面的面积;(2)求E1与BB1的距离。
Many weak points exposed by students in solving the problem of three-dimensional geometry, highlighting the poor spatial imagination, space concept fuzzy, resulting in errors in the calculation, argumentation, etc. This article is based on common mistakes to be analyzed for reference purposes only. First, the concept is not clear Example 1. A cube A1B1C1D1-ABCD edge length of a. (1) Cross the center E1, F1 and the center O of the bottom of A1D1, D1C1 on the two adjacent sides of the upper base, and find the area of this cross section. (2) Find the distance between E1 and BB1.