AMC10 2001 A
AMC10 2001 A · Q5
AMC10 2001 A · Q5. It mainly tests Basic counting (rules of product/sum), Symmetry.
How many of the twelve pentominoes pictured below have at least one line of symmetry?
下面图片中的十二个五连方中有多少个至少有一条对称轴？
(A)
3
3
(B)
4
4
(C)
5
5
(D)
6
6
(E)
7
7
Answer
Correct choice: (D)
正确答案：（D）
Solution
Exactly six have at least one line of symmetry. They are:
恰好有六个至少有一条对称轴。它们是：
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