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(1ij8),8121,,1aj-ai20(1ij8),20.,8.(i)8,14,aj-ai=am-ak(1ijkm8)..(ii)8,42,42(aj-ai=am-akaj=akai=am).,(ai,aj,ak),2aj=ai+ak(1ijk8).88(ai1,aj1,ak1),(ai2,aj2,ak2),,(ai8,aj8,ak8),,2ajl=ail+akl(l=1,2,,8).a1a8,6.,82,aj1=aj2.ai1+ak1=2aj1=2aj2=ai2+ak2,,ai1ak1ai2ak2(,).(i)(ii),n=8.(,210008)(7)(7,42)1.a1,a2,,an09,n+1a1a2an222a1a2an.n().(A)15(B)16(C)17(D)182.910,22().().(A)913711(B)916(C)912(D)9143.ABCDE,A=C=90,AB=BC=DE=AE+CD=3.().(A)9(B)1015(C)12(D)13154.x,yy1=2x,y2=x+3,y3=-x+3.y().(A)2(B)3(C)5(D)65.y=ax2+bx+c,,(1,0)(0,2).a().(A)a0(B)a-1(C)-2a0(D)-1a06.GABC,rABC,GBCCAABGDGEGF.s=1GD+1GE+1GF.().(A)s3r(B)s=3r(C)s3r(D)(7,28)1.6n(n+1)(n+2)(n+3)5220071nn+1n+2n+3,.2.ab,2a+b=2.4a2+1+b2+4.3.aba2=-1-5a,5b=-1-b2.bba+aab.4.ADABC,ADABCE.ABAC-BDDCAD2().(20)29a+30b+31c=2196.(25)ABCD,EFABAD,EFBD,EEMCDM,FFNBCN,EMFNACG.:ACBD.(25)ABC,b-ccotA2+c-acotB2+a-bcotC2=0.:b-ccot2A2+c-acot2B2+a-bcot2C2=0.1.C.,1,.1n17.2.D.60,1260,60,5,12.22,AOB,9x.9x-2,AC,x-212;9x+2,BD,(x+2)-35.AC=BD.,x-212=(x+2)-35.x=14.914.3.A.33,DCF,CF=AE,BEBDBF.DF=DE=3.BCFBAE,BE=BF.BD=BD,,BEDBFD.,SBED=SBFD.SABCDE=SBEDF=2SBFD=212DFBC=9.44.B.4,y1y2(3,6),y2y3(0,3).y=-x+3,x0;x+3,0x3;2x,x3.y3.5.C.a0,-b2a0,4ac-b24a0,a+b+c=0,c=2.62a+b+c=0c=2,b=-2-a.a0-b2a0,b0.,-2-a0,a-2.a0,b0,c=24ac-b24a0,a-2a0.6.B.55,AMBC,BGCG.SAGB=SAGC=SBGC=13SABC.SBGC=12BCGD,,1GD=BC2SBGC=3a2SABC.,1GE=3b2SABC,1GF=3c2SABC.1GD+1GE+1GF=3(a+b+c)2SABC.SABC=12(a+b+c)r,1GD+1GE+1GF=3r.1.1n-3n+1+3n+2-1n+3.6n(n+1)(n+2)(n+3)=3n(n+3)-3(n+1)(n+2)=1n-1n+3-3n+1-3n+2=1n-3n+1+3n+2-1n+3.2.13.66,AB=2,CDAB,CAAB,DBAB,CA=1,BD=2,EAB.AE=2a,BE=b.CEDECD.CE=4a2+1,DE=b2+4.CE+DECD,,4a2+1+b2+4CD.CED,4a2+1+b2+4CD.,ACEBDE.AEBE=ACBD,2ab=12.,b=4a,2a+b=2,a=13.,b=43.a=13,b=43,CD=13.4a2+1+b2+413.3.-521-23.a2+5a+1=0,b2+5b+1=0.a=b,a=-5212,bba+aab=a+b=2a=-521.ab,abx2+5x+1=0.,a+b=-5,ab=1,ab.,bba+aab=-baab-abab=-(a+b)2-2ababab=-23.4..77,BE.BAE=DAC,E=C,ABEADC.,ABAD=AEAC,ABAC=AEAD.BDDC=DEAD.-ABAC-BDDC=(AE-DE)AD=AD2.29(a+b+c)+(b+2c)=2196,31(a+b+c)-(2a+b)=2196.7220071abc,29(a+b+c)=2196-(b+2c)2196-(1+21)=2193.,a+b+c751829.31(a+b+c)=2196+(2a+b)2196+(21+1)=2199.,a+b+c702931.a+b+c=71,72,73,7475.a+b+c=71,,b=5-2a,c=a+66.b1,5-2a1.a2,a=12.,2.,a+b+c=72,73,74,75,17332410.,2+17+33+24+10=86().88.,ACD90ACB90,EMACFNAC.DDQBCQ,BBPCDP.BPACH,DQACH.EMCD,BPCD,EMBP,EGBH.ABH,AEEB=AGGH.ADH,AFFD=AGGH.ABD,EFBD,AEEB=AFFD.AGGH=AGGH,GH=GH.,HH,HBCD.,HCBD,ACBD.9,ABCI9r,BCCAABDEF;ABCBCCAABabc.AIIF,FAI=12A,IFAB,IF=r,AF=12(b+c-a).RtAFI,cotFAI=AFIF,cotA2=b+c-a2r.,cotB2=a+c-b2r,cotC2=a+b-c2r.(b-c)cotA2+(c-a)cotB2+(a-b)cotC2=(b-c)(b+c-a)2r+(c-a)(a+c-b)2r+(a-b)(a+b-c)2r=0.b-ccotA2=-(c-a)cotC2+(a-b)cotB2cotB2cotC2.1cotA2b-ccot2A2=(a-c)cotC2+(b-a)cotB2cotA2cotB2cotC2.c-acot2B2=(b-a)cotA2+(c-b)cotC2cotA2cotB2cotC2,a-bcot2C2=(c-b)cotB2+(a-c)cotA2cotA2cotB2cotC2.++b-ccot2A2+c-acot2B2+a-bcot2C2=(b-c)cotA2+(c-a)cotB2+(a-b)cotC2cotA2cotB2cotC2=0.(,233300)82