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CEMC Gauss (Grade 7), 2001

Geometry Difficulty 1.0 Junior Find the answer Canada

$BC$ is a diameter of the circle with centre $O$ and radius 5, as shown. If $A$ lies on the circle and $AO$ is perpendicular to $BC$ , the area of triangle $ABC$ is

(A) $6.25$ (B) $12.5$ (C) $25$ (D) $37.5$ (E) $50$

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