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学习了表面积之后,有的同学认为从立体图形中挖去一块后,表面积一定减少;也有的同学认为表面积不会减少反而会增加;还有的同学认为表面积不会变化。究竟谁说得对呢?其实,我们在解决问题时,要从整体着眼,变换不同的观察角度,考虑各种实际情况,就不会有管窥一斑、盲人摸象之嫌。【例题】在一个棱长为20厘米的正方体木块上,挖去一个长是20厘米,宽和高分别为2厘米的小长方体,求剩下部分的表面积。
After studying the surface area, some students think that after digging a piece from the three-dimensional figure, the surface area must be reduced; some students think the surface area will not decrease but will increase; some students think the surface area will not change. In fact, when solving problems, we should look at the whole from the perspective of changing different perspectives and consider all kinds of actual situations so that we will not have a glimpse of the suspicions of the blind people. 【Example】 In an edge length of 20 cm square block, dug a 20 cm long, width and height of 2 cm small cuboid, and seek the rest of the surface area.