决战2020年中考数学压轴题综合提升训练《三角形》

《三角形》ABCC

CDAB

CDAB

BD

AC

OACBDM

BCNCONDNMBNNBNMABCABCACBCABCDAB

CDABCDCABCACDACBBODOCOBDAC

BD

ACBDNBNDNDNMNBNM

ABC

D

ABE

BDCDCE

AHCE

H

CD

GAHBC

FADGCDEHCE

CGFCFG

ABC

D

ABCD

ABCDABAD

ABADCDCDABADGCDEAHCECGHGCHAGDGADAGDCGHGADGCHADGCDEADGCDEADCDGADGCHADGCDEASA），AHCE

H

CEACAECAHEAHCAHAFCEAHAGDAFCAGDAGDCGHAFCCGHCGFCFGABCADBC

BDDEEF

AC

AC

F

BC

EBAEC

ACcmDCeq

\o\ac(△,cm) ABCADBCBDDEEFACABAEECCCAEBAEAED

C

AEDAEECABBDDEABBDECDEDCABCABBCACABBDDCACDCACcm）．ABCBACABCO

O

EFAB

BC

F

AC

E

O

ODBC

DAOB

CAEBFEFODaCECFbabCEFeq

\o\ac(△,S) CEF ab

OAOBBACABC

AOB

OAB

OBA

EFABOABAOEABOBOFOABEAOOBAOBFAOEEAOBOFOBFAEOEBFOFEFOEOFAEBFOACB

O

ACODeq

\o\ac(△,S) CEF CECF）•OD

baababABCABACAD

BCDEAB

EBDADDEAC

ABBC

DEBDEABACBDCDADBCBCDEABDEBADCBDECAD BAADDECAABACBDCDADBC

ADBAD

ADBD

ABDEDE ADBAEDBDEBADBDEBAD ABCABAC

ABO

BC

D

AC

EBDCDDECD

DFAB

F

BCAFBF

BDADAB

OADBDABACBDCDDEEODDAE

DOEADBDADBABDABACCABDBCBDCDBD

ODx

ABx

AFBF

AF

AB

xBF

AB

xADBDDFABBDBFAB

xx

xOBODBDOBDBOD

BD ADABCE

ACBE

AD

FAEEFACBFSASADCGDB

AEEFGFAEAFEBFGAEEFGBFGAFEFAEAASADCGDB

AD

G

DGAD

BG

BGBF

ADG

AD

G

DGAD

BGADABCBDCDADCGDB

ADCGDBSAS），ACBGAEEFCADEFABFGGGCADGBFGBGBFACBFAD

G

DGAD

BG

BGBF

ADGBGBFG

BFGAEEFEAFEFAEFABFGGEAFADCGDB

eq

\o\ac(△,A)

eq

\o\ac(△,DC) GDBAAS），ACBGACBFBGBF

ADG

BGAC

ADGGCADADABCBDCDADCGDBADCGDBAAS），ACBGAEEFCADEFABFGGGCADGBFGBGBFACBF

AB

x

y

AB

OCAOB

AB

C

D

AB

D

DEOC

y

E

AOmBOn

mn

nnnm

ABD

ABOE

Pxx

AB

x

E

y

EPEFFFPnnnmnnmnnmnnmmn

A

BDE

xF

FD

GDGDF

BG

OExOCAOBBOCAOCDEOCEFOFEOBEGBOCAOCOEOFxADFBDGADFBDGSAS），BGAFxGAFEGBEGBGBExxxxOEFP

FMyMPNyNEm），

Pxx+4），PNxENmxPEFPENFEMFMyMFEFEMPENMFEEFMPENEFMPENAAS），MENPxFMENmx

Fmxmx），Fmxmxx

PABCAM

BCD

AMCD

CDCDE

BE DAM1），则AD BE BE

AM

O

D

AM

2），试判断AD

BE

D

AMAOBAOB解：（1））∵△ABCDECACBCCDCEACBDC

EACDDCBDCBBCEACDBCEADCBECACDBCESAS），ADBEABCBAC

AM

BCCAM

BACCAMADBEABCCDEABBCDCECACBDCEACDACBDCBBCEDCEDCBACDBCEACDBCESASADBEAOBAOB

D

AMACDBCECBECADABCCBEABCABCAM

BCAMBACBOA

D

AMABCDECACBCCDCEACBDCEACB

DCBDCBDCEACDBCEACDBCEACDBCESASCBECADBAMBOAABC

E

AB

D

CB

EDEC

AE

DB

AEDB AE

DB

AEDB

E

EFBC

AC

FABCABBCACE

ABAED

CBEDECCD

E

EFBC

AC

FABCAFEACBABCAEFEFCEBDEFAEEDECEDBECBECBFECEDBFECBDEFECBDEFECAAS），BDEFAEBD

E

EFBC

AC

FABCAFEACBABCAEFEFCEBDEFAEEDECEDBECBECBFECEDBFECBDEFECBDEFECAAS），BDEFAEBDAEDB

ABACAEB

AEABCABACeq

\o\ac(△,BC) ACE

ACEAECDECBBECDBEABCDEBDEBBDBE

CD

A

ANBC

N

E

EMCD

MABCECEDBNCN

BC

CMMD

CDANEMBANBEM ABCAE MNCMMNCN

CDCM

ECDEBCEBCECD

EDCECED

EDCABCECBACBABCACBECDEDC

EDECCD

ABCABACeq

\o\ac(△,A) ABCABCABCBAC ABC

ABC

AD

CBD

CA

EAEAB

ABACBDABACBCABCABCACABCABCBBCC

C

CH

ABHCAHAHCHBH

ACABBHAHS

ABAC

ABCABCADBAEBADEADABAEADADABDAEDSAS），

ADEADBBDDEABACBDAEACBD

CEBDCEDECBDEADCADCOAOBACCD

AC

DDCA

BOCABDCMAC

BDN

B DCMCNAOAOBBCOC

D

DEyEDECAOCDCAECDBCAECDEDCBCAEDCDECCOAAAS），DEOCECOAOEOCECDBEOEOBBEDEDBEDBEOAOBOBADBABANANBDCACDNDNCDNCANBCDNBANDCAACMDCNDCNACMASA），CMCNABCBDACCAC

EBC

DEE

EFDE

F

ABDF

BC

GABDFDEADFEAAFDCDEEFBDACDEFADBABDDEFABDFADFEABDFDEBDDE

ABDABDAFDEABDBDFAFDAFDBDFBDEBDFFDEBDDEDBEBED

BDE

BDCCDBECPABCACED

BC

DDAADFCP

FADFD

ABBDxDFy

y

xeq

\o\ac(△,AF) ADFAF

BDACBACECPACEACPPCEADFACPADCFAFDACBADFAFDDAFADFADFDA

AHBCABCAHBCABBHAH BH HDBDBHxDFy

ADFADF

DF DF

xxxBD ABCD

BCDABAC

MNDMDNMDN

DM

ABBMCNBDDM

ABM

ABN

ACBMCNBD

DM

AB

M

AB

N

ACBMCNBDBMCNBD

BMCNBDD

DEAC

AB

EABCABCDEACBEDABDECBBEDBDEBDEEDCBDBEDEEDNCDNEDMEDNMDNCDNEDMD

BCDEBDCDC