(1)∵AC⊥OD，∴AD弧=DC弧又AC=BD，∴AC弧=BD弧，∴AD弧=BC弧，∴AD弧=DC弧=BC弧，∴∠AOD=60°，∴∠A=30°∴AF=√(3²-1.5²)=3√3/2∴AC=2AF=3√3(2)连结OE，则OE⊥BD(3√3/2)²=DF×3，DF=9/4FO=3-9/4=3/4∴DF:FO=(9/4):(3/4)=3:1
