Orthocenters form an equilateral triangle
Source: 2019-20 International Dürer Competition, Category E ,P4
August 19, 2020
geometryEquilateral Triangle
Problem Statement
Let be an acute triangle with side of length . Say we reflect the points and
across the midpoints of and , respectively to obtain the points and . Assume that the orthocenters of triangles , and form an equilateral triangle.
a) Prove that triangle is isosceles.
b) What is the length of the altitude of through ?