(a) \(\frac{1}{12}.\)

Area of ΔAOF = \(\frac{1}{2}\) x OF x AO
∴ Area of hexagon ABCDEF = 4 x (Area of ΔAOF + Area of rectangle ABDE)
= 2OF × AO + ED × AE
= 2OF × AO + 2OF × 2AO
= 6(OF × AO)
∴ Required ratio = \(\frac{\frac{1}{2}}{6}\) = \(\frac{1}{12}.\)