In the figure below, P is a point on
the incircle of triangle ABC and TATBTC is the contact triangle.
If PA1, PB1, PC1, PA2, PB2, and PC2 are perpendicular to BC, AC,
AB, TBTC, TATC, and
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.