In the figure below, P is a point on
the arc TATC of the incircle of triangle ABC and TATBTC is the contact triangle.
If PA1, PB1, and PC1 are perpendicular to BC, AC,
and AB, respectively,
The contact triangle or intouch triangle or Gergonne triangle
of a triangle ABC is defined by the 3 tangency points of the
incircle on the 3 sides.