In the diagram, is the centre of a circle with radius , and and lie on the circle. is positioned inside the circle so that passes through and is perpendicular to .
If , what is the area of ?
, 2023
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Solution
Since is a square and its side lengths are integers, then its area is equal to a perfect square. Since the product of the areas of and (the rectangle) is equal to 98, then the area of is a divisor of 98. The positive divisors of 98 are 1, 2, 7, 14, 49, and 98. There are exactly two divisors of 98 that are perfect squares, namely 1 and 49. Since the area of is greater than the area of , then the area of is 49, and so the area of is 2 (since ). Square has area 49, and so . [[IMAGE0]] The perimeter of is equal to Since the side lengths are integers and the area of is 2, then either (and ), or (and ). If , then the perimeter of is . Since 30 is not given as a possible answer, then and the perimeter is .

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