9. As shown in Figure 2, in $\triangle A B C$, $A B=B C=10$, points $M$ and $N$ are on $B C$ such that $M N=A M=4$, and $\angle M A C = \angle B A N$. Then the area of $\triangle A B C$ is $\qquad$.
9. $\frac{50 \sqrt{57}}{19}$