2006 AMC 10A Problem 7

Below is the professionally curated solution for Problem 7 of the 2006 AMC 10A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2006 AMC 10A solutions, or check the answer key.

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Concepts:areaarea decomposition

Difficulty rating: 1190

7.

The 8×188 \times 18 rectangle ABCDABCD is cut into two congruent hexagons, as shown, in such a way that the two hexagons can be repositioned without overlap to form a square. What is y?y?

66

77

88

99

1010

Solution:

The rectangle's area is 818=144,8 \cdot 18 = 144, so the square formed has side 144=12.\sqrt{144} = 12.

Along the top edge the three equal horizontal pieces satisfy DE=y=FBDE = y = FB with DE+y+FB=18.DE + y + FB = 18. Hence 3y=18,3y = 18, so y=6.y = 6.

Thus, the correct answer is A.

Problem 7 in Other Years