解 过O作OF⊥CD于F,连结CO,∵AE=6cm,EB=2cm,∴AB=8cm∴OA=1/2 AB=4cm,OE=AE-AO=2cm,在Rt△OEB中,∵∠CEA=∠BED=30°,∴OF=1/2 OE=1cm.在Rt△CFO中,OF =1cm,OC＝OA＝4cm,∴CF=根号内（OC平方-OF平方）=根号15 cm．又...