11.3

1AB=AD,BC=DCA,ABAD,ACAE,AE?

2 ACDACB AD=AB DC=BC CA=CA ACD ACBSSS CAD=CAB ACDAB

ONOMCE

AOC

1AOB

2OCCDCDAB 3

(1)AOB (2):.

OC AOB 1= 2 PD OAPE OB PDO= PEO PDOPEO PDO= PEO 1= 2 OP=OP PDO PEOAAS PD=PE OCAOBPOCPDOADPEOBE: PD=PE(3)

(4) ?()

OABEDOCAOB ,P OC,PE=PD??CPPD,PEOA,OB,,

ABCC=90 ADBACDEABEFACBD=DF CF=EB :CF=EB,,RtCDF RtEDB. BD=DF(),DC=DE () HL.

1()2 3

1.OCAOB PD=PEPDOAPEOB

2.,ABCACBCADBACDEABAB7AC3BEEDCBA

3.RtABCBDABC DEABEDEAB10BC8AC6BEAEAED