Bunuel

In the figure above, a right triangle is located entirely inside a square with side length of 6. If all three side lengths of the right triangle are integers, what fraction of the square is shaded?
A. 1/6
B. 1/4
C. \(\frac{1}{\sqrt{3}}\)
D. \(\frac{\sqrt{2}}{3}\)
E. It cannot be determined
Attachment:
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MANHATTAN GMAT OFFICIAL SOLUTION:The area of the square is (6)(6) = 36. But what is the area of the shaded right triangle?
The constraint that all three sides of the right triangle must be integers is actually quite restrictive. The sides of the triangle must be a Pythagorean triple or a multiple thereof. The first few Pythagorean triples are 3–4–5, 5–12–13, and 8–15–17. Only 3–4–5 is compact enough to fit inside region D, since all other Pythagorean triples have a side longer than 6. We should also check whether ABC could be a multiple of 3–4–5. The smallest integer multiple of the 3–4–5 triple is 6–8–10, which certainly would not fit inside a 6 by 6 square.
Thus, we can conclude that ABC has sides of length 3, 4, and 5, and an area of 1/2*3*4 = 6.
The shaded area is therefore 6/36 = 1/6 of the area of the square.
The correct answer is A.