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近年来,以几何图形的运动为载体,求在运动过程中图形上某一线段扫过的区域面积问题,在中考试卷中屡有出现,不少同学对于此类题型感觉无从下手.下面通过具体实例来说明此类问题的解法.一、扫过区域为三角形例1如图1,等边△ABC中,BC=6,D、E分别在BC、AC上,且DE∥AC,MN是△BDE的中位线.将线段DE从BD=2处开始向AC平移,当点D与点C重合时停止运动,则在运
In recent years, the geometry of the movement as a carrier, seeking graphics in the movement of a line swept across the area of the area in the examination papers often appear, many students feel unable to start for such questions. Following through Specific examples to illustrate the solution of such problems. First, the region swept triangular Example 1 Figure 1, equilateral △ ABC, BC = 6, D, E respectively BC, AC, and DE∥ AC, MN is △ BDE of the median line. The line segment DE from BD = 2 began to AC translation, when the point D coincides with the point C to stop the movement, the transport