如图,已知△ABC内接于⊙O,AB是⊙O的直径,点F在⊙O上,且满足,过点C作⊙O的切线交AB的延长线于D点,交AF的延长线于E点.(1)求证:AE⊥DE;(2)若∠CBA=60°,AE=3,求AF的长.