A:Educated
B:To be educated
C:Educating
D:Having educated
如图,在△ABC中,BA=BC,以AB为直径的⊙O分别交AC,BC于点D,E,BC的延长线与⊙O的切线AF交于点F.
(1)求证:∠ABC=2∠CAF;
(2)若AC=210,CE:EB=1:4,求CE,AF的长.