A line can be specified in trilinear coordinates by parameters 
such that the trilinear
coordinates 
obey
 |
(1)
|
The trilinear line at infinity of a triangle with side lengths 
,
, and 
is
 |
(2)
|
The line passing through points 
and 
is given by
 |  |  |
(3)
|
 |  |  |
(4)
|
 |  |  |
(5)
|
Three trilinear points 
,
, and 
are collinear if
 |
(6)
|
Three lines
 |  |  |
(7)
|
 |  |  |
(8)
|
 |  |  |
(9)
|
concur iff
 |
(10)
|
in which case the point of concurrence is
 |
(11)
|
