2005 AMC 8 Problem 4

Attempt Problem 4 of the 2005 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2005 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

4.

A square and a triangle have equal perimeters. The lengths of the three sides of the triangle are 6.16.1 cm, 8.28.2 cm and 9.79.7 cm. What is the area of the square in square centimeters?
2424
2525
3636
4848
6464
Answer: C
Concepts:perimetersquare (geometry)
Small hint:
First find the triangle’s perimeter.
Big hint:
That perimeter is also the square’s perimeter.
Solution:
The perimeter of the triangle is 6.1+8.2+9.7=24 cm. 6.1 + 8.2 + 9.7 = 24 \text{ cm.} This means that the side length of the square is 24÷4=6 cm. 24 \div 4 = 6 \text{ cm.} Therefore, the area of the square is 62=36 cm2. 6^2 = 36 \text{ cm}^2.
Thus, C is the correct answer.
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