解:$\because \angle B = 45^{\circ},\angle ACB = 30^{\circ},$
$\therefore \angle A=180^{\circ}-\angle B - \angle ACB=180^{\circ}-45^{\circ}-30^{\circ}=105^{\circ}。$
又$\because \triangle ABC\cong\triangle DEF,$
$\therefore \angle D=\angle A = 105^{\circ},$$BC = EF = 5\mathrm{cm}。$
$\therefore FC=EF - CE=5 - 2 = 3(\mathrm{cm})$