如圖,BD=CD,AE∶DE=1∶2,延長(zhǎng)BE交AC于F,且AF=5cm,則AC的長(zhǎng)為()。
A.30cm B.25cm C.15cm D.10cm
A.1 B.5/6 C.1/6 D.1/30
A.2a B.a C.√3/2a D.12a