The reasons are as follows: In ABCO Square and ODEF Square, AO=CO solution: (1) ad = cf.

The reasons are as follows: in ABCO Square and ODEF Square, AO=CO, OD=OF, ∠ AOC = ∠ DOF = 90.

∴∠AOC ∠COD=∠DOF ∠COD，

That is ∠AOD=∠COF,

At △AOD and △COF,

AO=CO

∠AOD=∠COF

OD=OF

∴△AOD≌△COF(SAS)，

∴ad=cf；

(2) Use the same method as (1) to find CF=AD.

As shown in the figure, connect DF and OE to G, and then DF⊥OE, DG=OG=? OE，

The side length of a square ODEF is ∵ 2.

∴OE=√2×√2=2，

∴DG= 1

∴AG=AO OG=3 1=4，

At Rt△ADG, AD=

√AG2 DG2=√42 12=√ 17

∴CF=AD=√ 17