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2006 AMC 10B Problem 5

Problem 5 of 25EasierAlgebraGeometry

A 2×32 \times 3 rectangle and a 3×43 \times 4 rectangle are contained within a square without overlapping at any interior point, and the sides of the square are parallel to the sides of the two given rectangles. What is the smallest possible area of the square?

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Solution

Place the rectangles side by side with their 33-length sides vertical. Their widths add to 2+3=5,2+3=5, and the heights 33 and 44 both fit within 5.5. Because the rectangles are axis-aligned and their interiors do not overlap, their horizontal projections or their vertical projections must be disjoint. In either direction, the first rectangle spans at least 22 and the second spans at least 3,3, so the square’s side is at least 2+3=5.2+3=5. The smallest area is therefore 52=25.5^2=25. Thus, the correct answer is B.

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Concepts: square (geometry) · rectangle · optimization

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.