olymmath

RS-SMO 2023

Serbian Mathematical Olympiad 2023.

Official paper

The official paper in 1 language

Serbian

Other problems

Problem 6

Given is a triangle ABCABC with incenter II and circumcircle ω\omega . The incircle is tangent to BCBC at DD . The perpendicular at II to AIAI meets AB,ACAB, AC at E,FE, F and the circle (AEF)(AEF) meets ω\omega and AIAI at G,HG, H . The tangent at GG to ω\omega meets BCBC at JJ and AJAJ meets ω\omega at KK . Prove that (DJK)(DJK) and (GIH)(GIH) are tangent to each other.