Orthocenter and tangency point are collinear
Source: Sharygin Geometry Olympiad Correspondence Round 2017 P-3 (Grade-8)
May 1, 2017
geometry
Problem Statement
Let be the incenter of triangle ; the orthocenters of triangles and respectively; the touching point of the incircle with the side . Prove that and K are collinear.
Proposed by M.Plotnikov