[i]Let P be a point on the circumcircle of triangle [math]ABC[/math]; also let [math]P_1, P_2, P_3[/math] be reflections of P over sides [math]AB, AC, BC[/math], respectively. Then [math]P_1, P_2, P_3[/math] are all collinear with the orthocenter of the triangle.
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