C, D is on ⊙O, AB is the diameter, DE is the tangent of ⊙O, DE⊥AE.

∴AC⊥BC AD⊥BD DE⊥OD

∴AE‖OD BC

△ ADB △ AGD △ AGD = △ AED △ AEF △ DOF

AF:DF=AE:OD AG=AE

AC:OG=AB:OD=2: 1

∫AC:AB = 3:5

∴OG:AO=3:5

AG:AO=8:5

AO=OD

Silver: outside diameter =8:5

AF:DF=8:5