AMC 8 1990 Problem 25
AMC8 1990 年第 25 题
排列与组合★★★★☆
How many different patterns can be made by shading exactly two of the nine squares? Patterns that can be matched by flips and/or turns are not considered different. For example, the patterns shown below are not considered different.
通过恰好给九个正方形中的两个着色，可以形成多少种不同的图案？通过翻转和/或旋转能重合的图案不算不同。例如，下面显示的图案不算不同。
- A.3
- B.6
- C.8
- D.12
- E.18
正确答案 · Correct Answer
C
解析 · Solution
解析整理中
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