Problem

Source: Bundeswettbewerb Mathematik 2021, Round 1 - Problem 3

Tags: geometry, geometry proposed



Consider a triangle $ABC$ with $\angle ACB=120^\circ$. Let $A’, B’, C’$ be the points of intersection of the angular bisector through $A$, $B$ and $C$ with the opposite side, respectively. Determine $\angle A’C’B’$.