HMMT 二月 2008 · GEN2 赛 · 第 3 题
HMMT February 2008 — GEN2 Round — Problem 3
题目详情
英文原题
- [ 3 ] A 3 × 3 × 3 cube composed of 27 unit cubes rests on a horizontal plane. Determine the number ofways of selecting two distinct unit cubes (order is irrelevant) from a 3 × 3 × 1 block with the property
°
that the line joining the centers of the two cubes makes a 45 angle with the horizontal plane.
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解析
英文解析
- [ 3 ] A 3 × 3 × 3 cube composed of 27 unit cubes rests on a horizontal plane. Determine the number ofways of selecting two distinct unit cubes (order is irrelevant) from a 3 × 3 × 1 block with the property
°
that the line joining the centers of the two cubes makes a 45 angle with the horizontal plane.
Answer: 60 Same as Combinatorics Test problem 1.
2 2 2 2