Each of two equal circles $\omega_1$ and $\omega_2$ passes through the center of the other one. Triangle $ABC$ is inscribed into $\omega_1$, and lines $AC, BC$ touch $\omega_2$ . Prove that $cosA + cosB = 1$.
Problem
Source: Sharygin 2010 Final 10.2
Tags: geometry, trigonometry, circles, circumcircle, trigonometric