角平分線練習題

.-22ABCEBCFDFAB3C4D6BCABCDAOC=ODCDOEBOE.

-可編..-OPBOPBDOCDBD=2ABA2B2C2D3BACABDA6B8CD12RtBACCD=3AB=10ABDA15D10ABCBACBCDAB=10S

=15CDABD.

-可編..-A．3B．4C．5D．6BPDEA∠DBE=∠DBFC．2DF=DB∠BDE=OAOM⊥ACM⊥ABNOMAB．5cm．8cmD．20cm10AOBA．MB．NCD．Q11l.

-可編..-ABD12ABCBACDCD=BDDAB6BCA6B12C2413ABCADBACDEABEBDE=BACADCDEA1B2C3D414ABABD15PDPEACDEPD=PEAPD.

-可編..-APEABAAADHL16RtABCDBC=4cmCD=3cmDABAB3cmC4cm5cm17OCPDDPOBA1B2C3D418EABDCBCAEBADADE=DE=BEAD=AB+CD.

-可編..-AD19AABCBABCDABC20ABCADBACDEABEADCDEBAC=DEADBBE+AC=ABA2B3C4121RtABCABCACDAB=12CD=3DAB.

-可編..-A20D2422ABCABE

=10ABCA9B8C7D6

1323BDABCACDBCEBC=6S

=9DEABC24CMOBOC=5COA.

-可編..-25OBOCABCACBODBCDABC26OBOCABCACBODBCDABC27ABCABCBC=10cmBD2DAB28BACCD=16DAB.-可修編..-29BACDEABDE30c31OABCBOC=32RtABCACDBD=2AC=8ACD33BDBDCAFC.

-可編..-DGF=RtABCADBACBCDBC=32BD7DAB

536DEABEDFACFBE=CF1ADBAC2AE37EAOBECEDOBDECD=EDCOECD.

-可編..-38ABCDACBADAB=AD，EABAECFABCD39△ABCACBOOACEBE=EOOFCFBC=12cmOAB4cmOBC40ABC，ADCBDDDE⊥ABEEABCD=4BE.-可修編..-2322ABCEBCFDFA2B3C4D6BGABCDEABDFBCDBCADCMAB=.

-可編..-ABMNNB=ABCDDMADCADMCMBCMNADMBABMAB=B.

-可編..-AAOBBCDOEDAOE=BOEOEAAOBAOC=ODBCDOECDOPBOPBDOCDBD=2ABA2B2C2D3BBEEBOPOCDBD=2BE=BD=2ABE.

-可編..-∴AB=BE=2．故選：．中是的角平分線則△ABD的面積是（）A．6B．8C．10D．12【解答：如圖，過D作DE于E，CD=2∵AD∠BAC的平分，∠C=90°，∴DE=CD=2，eq\o\ac(△,∴)ABD面積=?DE=2=8．故選B．如圖中，是∠BAC的分線CD=3，AB=10，eq\o\ac(△,則)ABD的積于）.

-可編..-A．30．24C．15．10【解答：如圖，過D作DE⊥AB于E，∵AD平分BAC，，∴DE=DC=3，∵AB=10，eq\o\ac(△,∴)ABD的面積=?DE=：C．．如圖，△ABC，∠C=90°，AD平分BACBC于D，AB=10，S

=15，CD的△ABDA．3B．4C．5D．6【】D作DE⊥ABE∵∠C=90°，AD平分∠BAC∴DE=CD，.

-可編.∴S

.-AB?DE=10?DE=15DE=3ADBAEFADBE=BDE=DFCDBDE=BDFBPABCDEACDFABB△DBERt△DBF∴Rt△DBERt∴DBE=DBFBDFADDBCOABACOMACMNOM.

-可編..-A．4cmB．5cmC．8cm．20cmBACOM⊥AC⊥ABC10AOBA．MB．NCD．QMAOBAOBMA11lACD.

-可編..-D12ABCBACDCD=BDDAB6BCA6B12C24DDEABEDAB6DE=6ADBACDEABCD=DE=6CD=DBDB=12BC=6+12=18.

-可編..-13ABCADBACDEABEBDE=BACADCDEA1B2C3D4ADDEABCD=DEACDAEDRtACDRtHLAC=AEADC=ADEADCDEB+B+BDE=BAC.

-可編..-4D14ABABDAB15PDPEACDEPD=PEAPDAPEABAAADHLPDPEAC.

-可編..-ADP=ADPRtADPAEPHLD16RtABCDBC=4cmCD=3cmDABAB3cmC4cm5cmDDEABEABCABCBDACDDE=DC=3cmB17OCPDDPOB.

-可編..-A1B2C3D4PPEOCAOBPOCPEPE=PDPD=2PE=PD=2B18EABDCBCAEBADCDEDE=BEAD=AB+CDADEADF.

-可編..-ABBCAEBADRtRtAB=AFAEBEBCRtDC=DFCDEAD=AF+FD=AB+DCA19AABCBABCDABC.

-可編..-ABCB20ABCADBACDEABEADCDEBAC=DEADBBE+AC=ABA2B3C41BACDAC=DAEDEABC=AD=ADDACDAECDA=EDAADCDEDEAE=AC.

-可編..-BBBDE=BACBDEB21RtABCABCACDAB=12CD=3DABA20D24DDEABRtABCABCACDDE=DC=3DABB22ABCABE

=10ABC.

-可編..-A9B8C7D6DDFACFADABCDEABS

=DE=2=4ADBABC10ADC104=6DF=62=6D1323BDABCACDBCEBC=6S

=9DEABC.

-可編..-DFABFBDDEBCDFABDE=

DE+DE=9ABC24CMOBOC=5COA3CCFOCAOBCM.

-可編..-OM=4CM=3CF=3325ACBBCDABC96OOMABONACAOOBABCACBOM=ON=OD=6ABCABOM+BCDO+NO=AB+BC+ACDO=96.

-可編..-26OBOCABCACBODBCDABC42OOEABACFOAOBABCACBBCABCS

AOB

AOC

OBC=OD==.

-可編..-27ABCABCBC=10cmBD2DAB4cmBDDC=3DC=4cmADABCDABDCDAB4cm4cm28BACCD=16DAB16DDEABEDEDABCABDEABDC=DE=16.

-可編..-29ADBACDEABDE3ADADEDEDE=330c4ABCABCPABCPPEABBCACPF=PD.

-可編..-PABCABC344431OBOC=OABCOOBC+OCB=ABC+ABCOOCB32RtABCACDBD=2.

-可編..-AC=8ACD8DHACHCDACDDHACDH=DB=2ACD833BDBDCAFCBDDCAFCADBACCAD=DGF=CAD+.

-可編..-34

35RtABCADBACBCDBC=32BD7DAB14DDEABEBC=327ADBACDE=CD=14DAB14536DEABEDFACFBE=CF.

-可編..-BACAB+ACAEDEEDFFBDECDEBDEDE=DFADBAC2AB+AC=2AEBE=CFBACEAD=ADFAEDAFD.

-可編..-37EAOBECEDOBDECD=EDCOECDEECOAEDOBECD=2RtODERtOCEODEHLOC=ODAOBCD38ABCDBAD