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UKMT Senior Kangaroo, 2017

Geometry Difficulty 3.0 AMC 10/12 Prove it United Kingdom

The curve $x^2 + y^2 = 25$ is drawn. Points on the curve whose $x$ -coordinate and $y$ -coordinate are both integers are marked with crosses. All of those crosses are joined in turn to create a convex polygon $P$ . What is the area of $P$ ?

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