Problem

Source: 2023 Yasinsky Geometry Olympiad VIII-IX basic p5 , Ukraine

Tags: geometry, arcs



Point $O$ is the center of the circumscribed circle of triangle $ABC$. Ray $AO$ intersects the side $BC$ at point $T$. With $AT$ as a diameter, a circle is constructed. At the intersection with the sides of the triangle $ABC$, three arcs were formed outside it. Prove that the larger of these arcs is equal to the sum of the other two. (Oleksii Karliuchenko)