KöMaL 2020 C1612

The convex heptagon $A_1A_2A_3A_4A_5A_6A_7$ has a circumscribed circle centred at an interior point of the heptagon. Prove that the sum of the interior angles at the vertices $A_1$, $A_3$ and $A_5$ is less than $450^{\circ}$.