The Nobbs points of a triangle 
are the intersections of the corresponding sides of
and its contact
triangle 
, i.e., the first Nobbs point 
is the intersection of 
and 
, and similarly for 
and 
. The Nobbs points are collinear
and fall along the Gergonne line. They have trilinear
coordinates 
, 
, and 
.
Given the tangent circles of a reference triangle, the pairwise external centers of similitude are the Nobbs points.
