Darij Grinberg, On the Kosnita point and the reflection triangle,

Forum Geometricorum, 3 (2003) 105--111.

Abstract:   The Kosnita point of a triangle is the isogonal conjugate of the nine-point center. We prove a few results relating the reflections  of the vertices of a triangle in their opposite sides to triangle  centers associated with the Kosnita point.

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