∵∠CAB= 120，

∴∠CAH=60，

AC = 6，

∴AH=3,HC=33，

At Rt△BCH, ∫BC = 14, HC=33,

∴BH=BC2？ HC2= 142？ (33)2= 169= 13

∴AB=BH-AH= 13-3= 10

That is, the distance between a and b is 10 meter.