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CEMC Gauss (Grade 8), 2026

Geometry Difficulty 3.5 AMC 10/12 Find the answer Canada

In the diagram, the right-angled isosceles triangle has a
hypotenuse length of 8 cm\sqrt{8}~\text{cm}.

Figure 0

What is the smallest number of these triangles needed to completely
cover a square with side length 8 cm8~\text{cm}?

Pick one

Solution

Using the Pythagorean Theorem, we get x2+x2=82x^2+x^2=\sqrt{8}^2 or 2x2=82x^2=8. So, x2=4x^2=4 or x=2x=2 (since x gt;0\text{x gt;0}).

Thus, the right-angled isosceles triangle has area 12×2 cm×2 cm=2 cm2\dfrac12\times 2\text{ cm}\times2\text{ cm}=2\text{ cm}^2.

A square with side length 8 cm8\text{ cm} has area 8 cm×8 cm=64 cm28\text{ cm}\times8\text{ cm}=64\text{ cm}^2.

Thus, the smallest number of these triangles needed to completely cover
the square is 64 cm22 cm2=32\dfrac{64\text{ cm}^2}{2\text{ cm}^2}=32.

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.