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1、,12.2, ,1 ,1. 2. 3.,1. , .,3.ABC DEF.,AB=DE, CA=FD, BC=EF, A= D, B=E, C= F,2. ,.,ABCDEF?,1,1,2,.,.,2,1,2,3,:.,1,3,2,ABCABC ,AB= AB ,BC =BC, A C =AC.ABCABC,A ,B,C, 1BC=BC 2B,CAB,ACA 3AB,A C .,. SSS,ABC DEF, ABC DEFSSS.,1 AB =AC AD A BC D 1ABD ACD ,AD,AB=AC,BD=CD,DBC, D BC BD =DC ABD ACD , ABD ACD SSS
2、 ,(2)BAD = CAD.,1ABDACD BAD= CAD. , CBFAB =DC,AC=DF. :ABC DCF.,ABC DCF,AB = DC, ABC DCF,(),(),AC = DF,BC = CF,CBF,BC=CF.,(),(SSS).,: ,BECF , AB = DE , AC = DF ,BE = CF . : 1ABC DEF,2A=D.,:, ABC DEF ( SSS ).,ABC DEF,AB = DE AC = DF BC = EF,(),() (), BE = CF, BC = EF., BE+EC = CF+CE,1,2 ABC DEF A=D.,E
3、,DBC,BD=CD.,ABDACD,AB=AC,BD=CD,AD=AD,ABDACDSSS,2 , ABCAB=AC,ADABCDB=C.,B=C.,AOB AOB=AOB,3 ,O,D,B,C,A,O,C,A,B,D , 1O OA OB CD 2OAOOC OAC 3CCD 2 D 4D仭OBAOB=AOB,AOBAOB=AOB,1.DFBCAB=CEAF=DE ABFECD _ (.,BF=CD,2.ABCDADBC, ABCCDBABCCDAABD CDBBADC. ( ) A . 1 B. 2 C. 3 D. 4,C,=,=,3. AB=AEAC=ADBD=CE ABCAED.,B
4、D=CE,BDCD=CECD .,BC=ED .,=,=,ABCADE,AC=AD AB=AE BC=ED,ABCAEDSSS.,4. AC=FEAD=FB,BC=DE. (1)ABCFDE; (2) C= E.,(1) AD=FB AB=FD. ABCFDE ,AC=FE BC=DE AB=FD ABCFDESSS,=,=,?,?,2 ABCFDE., C=E.,5.,ADBC,ACBD.:CD .(: AB),AB,ABDBAC(SSS),AD=BC BD=AC AB=BA,ABDBAC,D=C.,6.ABACBDCDBHCH,ABDACD(SSS),ABHACH(SSS),BDHCDH(SSS), SSS),1. . 2. .,
