(1)∵∠ADB=90°
∴∠ABD+∠BAD=90°
∵∠BAD+∠CAE=90°
∴∠ABD=∠CAE
∵∠ADB=∠CEA=90° AB=CA
∴⊿ABD≌⊿CAE
∴AD=CE BD=AE
∵AE=AD+DE
∴BD=CE+DE
(2)CE=BD+DE.
∵∠ADB=90°
∴∠ABD+∠BAD=90°
∵∠BAD+∠CAE=90°
∴∠ABD=∠CAE
∵∠ADB=∠CEA=90° AB=CA
∴⊿ABD≌⊿CAE
∴AD=CE BD=AE
∵AD=AE+DE
∴CE=BD+DE
(3)(不便于画图,自己画图)DE=BD+CE.
∵∠ADB=90°
∴∠ABD+∠BAD=90°
∵∠BAC=90°
∴∠BAD+∠CAE=90°
∴∠ABD=∠CAE
∵∠ADB=∠CEA=90° AB=CA
∴⊿ABD≌⊿CAE
∴AD=CE BD=AE
∵DE=AD+AE
∴DE=CE+BD