1990 AMC 12 第 10 题
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所有题目均经美国数学协会（MAA）官方合法授权使用。
10.
一个 的木质立方体由 个单位立方体粘成。从一个观察点最多能看到多少个单位立方体？
An wooden cube is formed by gluing together unit cubes. What is the greatest number of unit cubes that can be seen from a single point?
小提示：
从一个观察点至多能看到立方体的三个面
At most three faces of a cube are visible from one point
大提示：
对三个两两相邻的 面应用容斥原理
Use inclusion-exclusion on three mutually adjacent faces
解答：
从适当的观察点可以看到三个两两相邻的面。它们共包含 个不同的单位立方体：减去三条重复计算的公共棱，再补回顶角处的单位立方体。
所以正确答案是 D。
From a suitable point one can see three mutually adjacent faces. They contain distinct unit cubes: subtract the three shared edges and restore the corner cube.
Thus the correct answer is D.
其他年份的第 10 题
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