Given triangle 
,
there are four lines simultaneously tangent to the incircle
(with center 
)
and the 
-excircle (with center 
). Of these, three correspond to the sidelines of the triangle,
and the fourth is known as the 
-intangent (Kimberling 1998, p. 161), illustrated above.
The intangents intersect one another pairwise, and their points of intersection form the so-called intangents triangle.
