初二数学上册北师大版知识点总结

11abc222cba232abc222cba3222cbaabc6,8,103,4,55,12,139,12,157,24,259,40,411aabb+c=a2a,b,c.3,4,55,12,137,24,259,40,41222n(n1)2n,n2-1,n2+16,8,108,15,1710,24,2641///2////3a2+b2c2~a2+b2=c2~a2+b2c2~a..b.c.41.34103x4xx=23x=64x=8681.1AB2.5AACBC1.5DE2BD=0.5AAAEAEABBCACECRtACBAC2=AB2-BC2=2.52-1.52=4AC=2BD=0.5CD=2EC=1.50.55.AD=12mCD=9mADC=90AB=39mBC=36mBDACRtADCABCAB2=15212161.ACSSABCACD12132,72/3+834sin60o1aba+b=0a=b2|a|0|a|=aa0|a|=-aa03abab=11-1451.1xax2=axa00aa2xax2=axaaaaaaa03xax3=axa3a33aa1xyxy53022||xyxy5030530||||212ab3ab4abbaba5abbaba226ab,1/a1/bab;1/a1/bab1a21)0()(2aaa2aa2)0(aa3)0,0(?babaab)0,0(?baabba4)0,0(bababa)0,0(bababa3a12123abba)()(cbacbabaab)()(bcacabacabcba)(.nn___________123412.12/0~360021132143154122222nnnn111341212/345123360360n(n-2)1803606nnn-3nn-22)3(nn12123412312132435445S==ah1212343121324S==1212343121324S==ab3~1012123434abS=222ba1.20cm12ABCD20cmAB=5cmABCEBAE=30ACBDOABCAC=5306012121212,3431231DEABCDSABCD?)(212BACABDSSBOCAODSSBCDADCSS1234567118021233.ABCO1801AOAO=AO2BOBO=BO3COCO=CO4ABBCCAABC.ABCDAC=BDACDEACEDDE=BD1=22=31=3DBCACBDB=AC1=3BC=CBDBCACBSASDC=ABABCD1.ABCDAB=4BC=8ACDDAECCD=CD=ABCED=AEBD=B=90