1、:K1-1.XOABCPlBC:yPA=PB+PC.1-2.XmPABC3?:yPA PB+PC.2.XP3ABC3eABCnSu120yPA+PB+PCkAPB=BPC=CPA=120.(:K)13.XlY+:A!BlAllAA=1BllBB=2AB=2y3I5yA!BlY+XF+olUn/ABPCSuOPA!BCyAB PC+AC PB=BC PA.4-2.Xm?o:ABPCPA!BCyAB PC+AC PB BC PA.(Vn/umo:E)5.X1/ABCDS:PPA+2PB+5PC.(:K)3:K)1-1.XOABCPlBC:yPA=PB+PC.1-2.XmPABC3?:yPA PB+
2、PC.1-1.y 3AP :P PB=PP BPA=BCA=60 BPP ABP =CBPABP =CBP(SAS)dPA=PP +P A=PB+PC.1-2.yBPC7:B=60BP ABPP dPA PP +P A=PB+PC.42.XP3ABC3eABCnSu120yPA+PB+PCkAPB=BPC=CPA=120.(:K)yBCeBCDADBCDu:P?:P dK(P A+P B+P C P A+P D AD=P P-dw,kAPB=BPC=CPA=120.5ABC,SXBACu120P3A:?PA+PB+PCvd:PABC:.?:n/I53n/OE,kU.53.XlY+:A!BlAl
3、lAA=1BllBB=2AB=2y3I5yA!BlY+XF+olUZYI+o.)ABABCCP 0 luP0u?:PPP ld1K(kPA+PB+PP PC+PP CP 0=P0P 0+P0C=P0A+P0B+P0C=CP0.+o.e;,5CP 0.AB0 BBAB0AB0C0(dAB0B=AC0C):BdB0 B:CdC0 CCH CP 0CC0H=30dkCP 0=CH+HP 0=12CC0+C0C0=12+1+3=1.5+3.64-1.Xo/ABPCSuOPA!BCyAB PC+AC PB=BC PA.4-2.Xm?o:ABPCPA!BCyAB PC+AC PB BC PA.(Vn/um
4、o:E)4-1.y3PA:P ABP =CBPqBAP =BCPkABP CBPqBP P=180 BP A=180 BPC=BACBPP =BCAkP BP ABCukABBC=P APC ACBC=P PPB dAB PC+AC PB=BC P A+BC P P=BC PA.4-1.yBPC7:B=qBP AdBABC=BP BP 9ABC=P BPP BP ABC a qkAB PC+AC PB=BC P A+BC P P=BC (P A+P P)BC PA.5ABCn/K1K1(Vn.3|enXSLVn3Ae.XAK1U:(VnXer(:.75.X1/ABCDS:PPA+2PB+5PC.(:K)ABO3:QQB:QA=1:2dVn?:PkPAQB+PBQA ABPQ=PA+2PB 5PQ=POCQ:dkPA+2PB+5PC 5(PQ+PC)5CQQH BCuHQH:BH=1:2QH=15BQ=15BH=2BH=25uCQ2=QH2+CH2=(15)2+(1+25)2=25CQ=10.5:nn:XU=m p)Xln;(89
