The Gossard perspector, also called the Zeeman-Gossard perspector, is the triangle center 
at which a reference triangle and its Gossard
triangle are perspective (Kimberling).
Suppose the Euler line of 
intersects the sidelines 
, 
, and 
at distinct finite points 
, 
, and 
, respectively, and that the three corner triangles 
, 
, and 
have defined Euler lines.
These three Euler lines form the sidelines of the Gossard
triangle and have the directions of 
, 
, and 
, respectively. The Gossard triangle
is the image of 
under a 
rotation about the perspector, which lies on their common
Euler line (Kellogg 1916, Kimberling).
The perspector is halfway from the triangle centroid of 
to the point given by the arithmetic mean of the
position vectors of 
, 
, and 
(Kimberling). It is the Dao-Zeeman
perspector of the Euler line.
