Let AD=x, then BD = 50× 20-x =1000-x. 。
∫∠EAC = 60,
∴∠CAB=90 -60 =30。
In Rt△BCD,
∫∠FBC = 45,
∴∠CBD=∠BCD=45,
∴CD=DB= 1000-x.
In Rt△ACD,
∫∠CAB = 30,
∴CD=tan30? AD,
That is db = CD = tan 30? AD= 1000-x=33x,
Solution: x≈633.98,
∴CD= 1000-633.98=366.02.
A: The distance from Building C to AB Expressway is 366.02 meters.