2001 AMC 10 Problem 5
Below is the professionally curated solution for Problem 5 of the 2001 AMC 10, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2001 AMC 10 solutions, or check the answer key.
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Difficulty rating: 1120
5.
How many of the twelve pentominoes pictured below have at least one line of symmetry?
Solution:
Checking each pentomino for a reflection line, exactly six have at least one: the straight bar, the plus, the T-shape, the U-shape, the V-shape, and the W-shape. The remaining six have no line of symmetry.
Thus, the correct answer is D.
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