1. Introduction
If S is a point belonging to the circumcircle of triangle ABC, then the images of
S through the reflections with axes BC, CA and AB respectively lie on the same
line that passes through the orthocenter of ABC. This line is called the Steiner line
of S with respect to triangle ABC.
If a line L passes through the orthocenter of ABC, then the images of L through
the reflections with axes BC, CA and AB are concurrent at one point on the
circumcircle of ABC. This point is named the anti-Steiner point of L with respect
to ABC. Of course, L is Steiner line of S with respect to ABC if and only if S
is the anti-Steiner point of L with respect to ABC. In 2005, using homogenous
barycentric coordinates, Paul Yiu [5] established an interesting theorem related to
the Feuerbach point of a triangle; see also [3, Theorem 5].