Centroamerican Math Olympiad 2017 - P3
Source:
June 23, 2017
OMCCOMCC 2017CENTROgeometrygeometric transformationreflectioncircumcircle
Problem Statement
Let be a triangle and be the foot of the altitude from . Let be the line that passes through the midpoints of and . is the reflection of over . Prove that the circumcentre of lies on the line .