orthocenter construction using a ruler at most with 6 lines
Source: 2022 Oral Moscow Geometry Olympiad grades 10-11 p4
April 18, 2022
geometryconstructionorthocenterRuler
Problem Statement
An acute-angled non-isosceles triangle is drawn, a circumscribed circle and its center are drawn. The midpoint of side is also marked. Using only a ruler (no divisions), construct the triangle's orthocenter by drawing no more than lines.(Yu. Blinkov)