∴∠DAC=∠BAE=90,
∴∠DAB=∠EAC,
AD = BD,AE=EC,
∴∠DAB=∠DBA,∠ECA=∠EAC,
∴∠DBA=∠ECA,
∴△ADB∽△AEC,
∴S△ADBS△AEC=(ABAC)2,
∫∠BCA = 90 degrees,
cos∠BAC=45=ACAB,
∴s△adbs△aec=25 16;
(2) The intersection point E is EH⊥AC, and AB extends to G to connect DG.
AE = EC,
∴AH=CH,EH⊥AC,
∫∠BCA = 90 degrees,
∴GH∥BC,
∴AG=BG,
AD = BD,
∴DG⊥AB,
∵AD⊥AC,AE⊥AB,
∴GE∥AD,DG∥AE,
∴ Quadrilateral is a parallelogram,
∴AF=GF,
∴AFFB= 13.