MathDB
Equal distance to triangle vertices

Source: Spain MO 2023 P6

March 12, 2023
geometrySpain

Problem Statement

In an acute scalene triangle ABCABC with incenter II, the line AIAI intersects the circumcircle again at DD, and let JJ be a point such that DD is the midpoint of IJIJ. Consider points EE and FF on line BCBC such that IEIE and JFJF are perpendicular to AIAI. Consider points GG on AEAE and HH on AFAF such that IGIG and JHJH are perpendicular to AEAE and AFAF, respectively. Prove that BG=CHBG=CH.