由图得：四边形ABCD是平行四边形,∴AB∥＝CD,O是对角线交点,∴OA=OC,易证△AOF≌△COE,∴OE=OF,CE=AF,设CE=x,则AF=x,FB =4－x,OE=y,则EF=2y,∴由周长=3＋x＋2y＋4－x=9.6,∴y=1.3即OF=1.3