【2021中考数学】三角形的内切圆专题

三角形内切一选题ABC80ABCA

B160

C80

DABCC58OABCA

B120

C

Deq\o\ac(△,Rt)ABC3BC4Oeq\o\ac(△,Rt)OBCACOCCDA

B2C

DIABcmIA1B2C3cmDlABClABCPCBl1

BAA'eq\o\ac(△,A)eq\o\ac(△,)CP'A'lBBPPlPCBCPPlBD'lPB'ABCACBAC36BCDACBEADFAEFAABC

B

CBCE

DABCIABDEBCA60

B130

C50

D65ABCABCD322

A64

B120

C

DIABCAOBACAIBAOB

BD10AB10OC

CEDECGCECBPQOPBADABCGDPAOCCBGDOP

A2

B3CD0ABCOABCADFABAC56DE1263

13ABCcb+|c3|+a

ABC14A30BCBPC1CP2CIB的15IAIDACB70DBI16AC2IADB4512BI4

17DOABCEDADCDO1DE2BD3OFPABCPF18IAIBCBDBI12OIAIOI5

ACO参答一选题ABC+A100OBC+OCB+DABCAOBOCBABAOCABAOBCAB+CBAC58CAB+AOBOOEACOFOHABHAOBOeq\o\ac(△,Rt)ABCOHOEOHABC45SS+△△△eq\o\ac(△,S)43OH3+6

2222222222OEOFOH1OFBCOHOFBHOHCF3eq\o\ac(△,Rt)ABCOCEOC90COFAAS3ODBCOCEODDCOD

+OE

CDCDDDGBCGDGOFBCODDGDGOF1ABCDGC

DC7

AIBIIIAIBCABCBACAIDAICBIEBIACBIDIACEIBCCAIDIACBIEIBDAIDIADADIEBEIDEDIDE+DA4DCPPPPBABCCPCPPCP2+PCP180PACP

ACBACBACBB2ACPPCP180CPPl

A8

BCAPCAPCPPlPCPAB36ABCACB36ADBCABACBEEBAEBCCBEFFFABCIFIEB6070A1807050IBCABIFIEACA50FIED

659

CBD32BACEBC+642BEC58CABCAOB2CAOBI180+CAB+C90+C2CAOB2+AOBAIBAOBC10

ODODDG90GDP+GEAB+OAODOADODAGPDGDPGPDGPGDACBACP+90+90ACEABCCAPABCPACAQC+CAP90ACP+PCQPQCPQ

DGBCODDGODBC

DOB6030OAOCOAACEOCEOPAPOAOEHABCADFOAOEODBDAOOAEeq\o\ac(△,Rt)AE4

222BDADOrODrreq\o\ac(△,Rt)AODrrreq\o\ac(△,Rt)BOEBDOEODOBEHDEOBOEHE

DE

12IABCABCI23

222222222△222222222△13+|c3|+a

193|+4+0ca453c+a

90rr+4rr5r14CPAPCAC42IBPCIBCPBCICBBIC180IBCICB180ABCACBBPC+BPC30BPC130BIC15515515IBADCADABICBICBDBADCBDBIDBAD+IBDCBI+CBDBIDDBIACB

ADB70BIDDBI555516AC90ADB45ADBBDCBC22AIIADCDAICAIAIBDAI+ADIBAI+CAIBACADIBIBCBI17

2222222222222OCCD⊙CDACO+ECDEDADAOAOCAECDDE22OA1CDCD1+BDEDADDE3BDCDDE1+2+BD

ADCADCADBD2+BD

222222222EDADDE3BDCDDE2+

3PBCFACBABABC1ABP122+3+APCFACB

ACFABABCCABCAPBAPBAPBAFCAP18IABC