∠1=∠2,
AB=AD,∠ABD=∠ADB=（180°-∠1）/2=90°-∠1/2,
AC=AE,∠ACE=∠E=（180°-∠2）/2=90°-∠2/2=90°-∠1/2=∠ABD=∠ADB,
AF平分∠BAC,
∠BAD=∠DAC=∠1=∠2,
∠BAC=∠BAD+∠DAC=∠1+∠1=2∠1,
∠DAE=∠EAC+∠DAC=∠2+∠1=∠1+∠1=2∠1,
∠BAC=∠DAE,
AB=AD,AC=AE,
△BAD≌△DAE,[SAS]
∠ACB=∠E=90°-∠1/2,
∠ABC=∠ADC,
∠ABC=180°-∠BAC-∠ACB=180°-2∠1-(90°-∠1/2)=90°-3∠1/2=∠ADC;
∠DCB+∠ACB=∠E+∠1,
∠DCB=∠E+∠1-∠ACB=90°-∠1/2+∠1-(90°-∠1/2)=∠1,
∠DBC=∠DBA-∠ABC=90°-∠1/2-(90°-3∠1/2)=∠1,
所以,∠DCB=∠DBC,
DC=DB,
即DB=CD.