Let △ABC be any given triangle. Let the
medians through the vertices A, B, C meet the
circumcircle of △ABC at A', B', C' respectively. Let △DEF be
the triangle formed by the
tangents at A, B, C to the circumcircle of △ABC. (Let D be the vertex opposite to the side formed by the tangent at the vertex A, E be the vertex opposite to the side formed by the tangent at the vertex B, and F be the vertex opposite to the side formed by the tangent at the vertex C.) The lines through DA', EB', FC' are
concurrent. The point of concurrence is the Exeter point of △ABC.