Collinearities and Concurrencies: Sides of Cevian Triangle.
If the sides of the Cevian triangle are extended, they intersect the sides of the ABC in three new points
, , and (or at the infinite point). These three points do not form a triangle, but are collinear.
The line containing these points is called the Axis of Perspective or the Tripolar Line.
Notice that is collinear with B and C and with and , making a point of concurrency.