AMC 8 1999 Problem 20
AMC8 1999 年第 20 题
立体几何★★★☆☆
Figure 1 is called a "stack map." The numbers tell how many cubes are stacked in each position. Fig. 2 shows these cubes, and Fig. 3 shows the view of the stacked cubes as seen from the front.
Which of the following is the front view for the stack map in Fig. 4?
图 1 称为「堆叠图」。数字表示每个位置堆叠了多少个正方体。图 2 显示了这些正方体，图 3 显示了从前面看到的堆叠正方体的视图。
下列哪个是图 4 中堆叠图的前视图？
正确答案 · Correct Answer
B
解析 · Solution
Solution 1
The third view is a direct, head-on view of the cubes. Thus, you will only see the highest (or, in these cases, higher) tower in each up-down column. For figure 4:
The highest tower in the first up-down column is 2 in the upper-left box.
The highest tower in the second up-down column is the 3 in the lower-middle box.
The highest tower in the third up-down column is the 4 in the upper-right box.
Thus, the head-on view of this tower should have 2 boxes on the left, 3 in the middle, and 4 on the right.
Diagram shows this description.
As trivia, option C shows the stack from the point of view of an observer on the right, facing towards the left.
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