MathDB
tangent lines at given youchpoints wanted, incenter, circumcircle related

Source: 2014 Croatia MO p7

August 5, 2020
geometryincentercircumcircletangent

Problem Statement

Let point II be the center of the inscribed circle of an acute-angled triangle ABCABC. Rays AIAI and BIBI intersect the circumcircle kk of triangle ABCABC at points DD and EE respectively. The segments DEDE and CACA intersect at point FF, the line through point EE parallel to the line FIFI intersects the circle kk at point GG, and the lines FIFI and DGDG intersect at point HH. Prove that the lines CACA and BHBH touch the circumcircle of the triangle DFHDFH at the points FF and HH respectively.