HMMT November 2022 U20

Let $\triangle A B C$ be an isosceles right triangle with $A B=A C=10$. Let $M$ be the midpoint of $B C$ and $N$ the midpoint of $B M$. Let $A N$ hit the circumcircle of $\triangle A B C$ again at $T$. Compute the area of $\triangle T B C$.