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若记平面内的封闭图形为F,在这个平面内建立直角坐标系后,按照斜二测画法(横不变,纵减半,角45°)画出这个图形的直观图F′与原图形F比较,形状有明显不同,且由于图形在直角坐标系中的位置不同,得到相应的直观图的形状也可能不同,我们的问题是:它们的面积是否相等?倘若不相等,那么它们的面积与原图形的面积有着怎样的关系?本文将解决这些问题.
If the closed figure in the inscription plane is F, after establishing a rectangular coordinate system in this plane, the visual map F′ and the original of this figure are drawn according to the oblique second survey method (horizontal invariance, vertical reduction by half, angle 45°). Compared with figure F, the shape is obviously different, and because the position of the figure in rectangular coordinate system is different, the shape of the corresponding intuitive figure may also be different. Our question is: Is their area equal? If they are not equal, then their What is the relationship between the area and the area of the original graphics? This article will address these issues.