Answer:
2.8
Step-by-step explanation:
By the angle bisector theorem, [tex]\frac{AC}{AB}=\frac{CD}{DB}.[/tex] Plugging in the values from the diagram gives:
[tex]\frac{5.8}{5.5}=\frac{3}{?}.[/tex]
Solving gives
[tex]?=(3\cdot 5.5)/5.8\\\approx 2.8[/tex]
