3. As shown in Figure 1, in Rt $\qquad$ $A B C$, $\angle B A C=90^{\circ}, A B=4$, $B C=12, A D \perp B C$ at point $D$, the angle bisector of $\angle A B C$ intersects $A C$ and $A D$ at points $E$ and $F$ respectively. A line through $F$ parallel to $B C$ intersects $A C$ at point $G$. Then the length of $F G$ is ( ).
(A) 10
(B) 6
(C) 8
(D) 9