2015 AMC 8 第 12 题
先试着解答 2015 AMC 8 第 12 题，然后核对你的答案与视频与精心整理的解答，解答来自 LIVE by Po-Shen Loh。你也可以参加完整限时模拟考试、查看全部 2015 AMC 8 解答，或核对答案。
所有题目均经美国数学协会（MAA）官方合法授权使用。
12.
一个立方体有多少对平行棱，例如 和 ，或 和 ？
How many pairs of parallel edges, such as and or and does a cube have?
小提示：
按方向给立方体的棱分组
Group cube edges by direction.
大提示：
每条棱与另外三条棱平行，但按棱统计会把每对数两次
Each edge is parallel to three other edges, but pair-counting double counts.
视频讲解：
Click to load, then click again to play
文字解答：
立方体有 条棱。对任意一条棱，都有另外 条棱与它平行。
这样每一对平行棱都被数了两次，所以平行棱对数为 。
所以正确答案是 C。
A cube has edges. For any edge, there are other edges parallel to it.
This counts each pair twice, once from each edge in the pair, so the number of pairs of parallel edges is
Thus, C is the correct answer.
其他年份的第 12 题
- 1985 AMC 8
- 1986 AMC 8
- 1987 AMC 8
- 1988 AMC 8
- 1989 AMC 8
- 1990 AMC 8
- 1991 AMC 8
- 1992 AMC 8
- 1993 AMC 8
- 1994 AMC 8
- 1995 AMC 8
- 1996 AMC 8
- 1997 AMC 8
- 1998 AMC 8
- 1999 AMC 8
- 2000 AMC 8
- 2001 AMC 8
- 2002 AMC 8
- 2003 AMC 8
- 2004 AMC 8
- 2005 AMC 8
- 2006 AMC 8
- 2007 AMC 8
- 2008 AMC 8
- 2009 AMC 8
- 2010 AMC 8
- 2011 AMC 8
- 2012 AMC 8
- 2013 AMC 8
- 2014 AMC 8
- 2016 AMC 8
- 2017 AMC 8
- 2018 AMC 8
- 2019 AMC 8
- 2020 AMC 8
- 2022 AMC 8
- 2023 AMC 8
- 2024 AMC 8
- 2025 AMC 8
- 2026 AMC 8