4 projections of foot of altitude are collinear
Source: 1985 German Federal - Bundeswettbewerb Mathematik - BWM - Round 1 p2
November 21, 2022
geometrycollinearprojectionsaltitude
Problem Statement
Prove that in every triangle for each of its altitudes: If you project the foof of one altitude on the other two altitudes and on the other two sides of the triangle, those four projections lie on the same line.