MEMO 2011 ekipno problem 6
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Avg: 6,0 Let be an acute triangle. Denote by and the feet of the altitudes from vertices and , respectively. Let be a point inside the triangle such that the line is tangent to the circumcircle of the triangle and the line is tangent to the circumcircle of the triangle . Show that the line is perpendicular to .
Izvor: Srednjoeuropska matematička olimpijada 2011, ekipno natjecanje, problem 6