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1、2.5 ,2 ,5 (SSS),1. 2.,ABCABCAB=ABBC = BCAC= AC ABCABC,A=AABCABC.,任ABC , ,ABC任BC A ABC任, 1=23=4.,1+3=2+4, , , SAS., ABC ,. SSS,ABC DEF, ABC DEFSSS.,1 AB=CD BC=DA. B=D., ABCCDA(SSS)., B =D.,2 ABCAB=ACDE BCAD=AEBE=CD. ABDACE., BE = CD, BE-DE = CD-DE., BD = CE.,ABDACE, ABDACE SSS., CBFAB =DC,AC=DF. :ABC
2、 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,(1),(2),(3)仯,.,.,SSS,?,1.,2.EFABCD( ),A. B. C. D.,D,D,1.DF
3、BCAB=CEAF=DE ABFECD _ .,BF=CD𰸲,2.ABCDADBC, ABCCDBABCCDAABD CDBBADC. ( ) A . 1 B. 2 C. 3 D. 4,C,=,=,3. ( ) A., B. C. D,C,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.ABACBDCDBHCH,ABDACD(SSS),ABHACH(SSS),BDHCDH(SSS),SSS.,.,