If 
and 
are distinct trilinear points, neither lying on a sideline
of the reference triangle 
, then the crosssum of 
and 
is the point
 |
It is the crosspoint of the isogonal conjugates of 
and 
. Therefore, 
is the isogonal conjugate of the 
-cross conjugate of the isogonal conjugate of 
, and 
is the isogonal conjugate of the 
-cross conjugate of the isogonal conjugate of 
.
