The circumcevian triangle of a point
with respect to a triangle
has vertices
at the second intersections of the lines
,
, and
with the circumcircle of
,
respectively (Kimberling 1998, p. 201). Configurations in which an intersection
is undefined or the resulting triangle is degenerate
are excluded.
The circumcevian triangle with respect to the point
has trilinear
vertex matrix
|
(1)
|
and area
|
(2)
|
where
is the area of
and
|
(3)
|
Circumcevian triangles for various choices of are summarized in the table below.
| Kimberling | circumcevian point | circumcevian triangle |
| incenter | circumcircle mid-arc triangle | |
| triangle
centroid | circum-medial triangle | |
| orthocenter | circum-orthic triangle |
Every triangle inscribed in the circumcircle of a reference triangle is congruent to exactly one circumcevian triangle of
(Kimberling 2005).
The circumcevian triangle of is similar to the pedal
triangle of
(Kimberling 1998). When both triangles are defined and
nondegenerate, their corresponding sides are parallel iff
lies on the M'Cay
cubic. When the resulting homothecy has a finite
homothetic center, that center lies on the Lemoine cubic (Gibert).