3. In the ellipse $\Gamma: \frac{x^{2}}{2019}+\frac{y^{2}}{2018}=1$, $F$ is the left focus. A line $l$ that does not pass through point $F$ intersects the left directrix of the ellipse $\Gamma$ and the ellipse $\Gamma$ successively at points $C$, $A$, and $B$. If $\angle F A B=$ $40^{\circ}, \angle F B A=10^{\circ}$, then $\angle F C A=$
3. $15^{\circ}$.

As shown in Figure 2, draw perpendiculars from points $A$ and $B$ to the left directrix, intersecting the left directrix at points $D$ and $E$ respectively.
By the second definition of an ellipse, we have
$$
\begin{array}{l}
\frac{C A}{C B}=\frac{A D}{B E}=\frac{A F}{B F} \\
\Rightarrow C F \text { is the external angle bisector of } \angle A F B \\
\Rightarrow \angle C F A=\frac{1}{2}(\angle F A B+F B A)=25^{\circ} \\
\Rightarrow \angle F C A=\angle F A B-\angle C F A=15^{\circ} .
\end{array}
$$