2021-2022学年湖北省恩施州恩施市八年级（上）月考数学试卷（9月份）（附答案详解）

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2021-2022
ᓅḕ឵឵ᛢ
ᨴὃᦪᔁ9ᨴ1.ᑡḄᱯ#Ḅᨵজᔜ'()*ঝᔜ,ᑁ.'()*ঞᔜᩩ1.23'()*টᔜ,᜜.'()*ঠ78,⚔:;<Ḅ1.2=nᑖᡂ☢A()Ḅ5-2,E.A.2,B.3,C.4,D.5,2.7FḄ8,⚔:

1C.50°D.60°7.8,~8,.Hᡂi8,Ḅᑁ.XT720஺HklḄᦪTA.5B.5ᡈ6C.5ᡈ7D.5ᡈ6ᡈ78.ᙠABC஺H4=4B=4C,:EᙠABHZ.AED=60°,ᑣ8ᨵA.^ADE=20°B.Z.ADE=30°C^DE=^ADCD-^DE=^ADC9.᝞cH:ᙠ8V2,4B஻DC,DE஻GF,NB=ZF=72°,ᑣND=u.10.8,Ḅᑁ.v140஺Hᑣy,Ḅᦪv.11.}஻ᑁ.XT1260uHᑣy,஻Ḅ1.2ᐳᨵ.12.Ḅ8,᜜.v72஺Hᑣy,Ḅᑁ.XḄuᦪv.13.᝞cᡠeHN1+/2+N3+N4+N5+46=.14.p☢H=3()ḄE.ஹஹrஹFḄ8ᔠᙠ8H᝞cHᑣ43+41—N2=15.8,Ḅᑁ.XḄ᜜.X540஺Hy,Ḅᦪ.16.᝞cHr48CDEḄᔜ,ᑁ.'()H4F஻CCh஺8Ḅ|32:HhOEḄ|32:G,}NGDF=70஺HNFB4Ḅuᦪ.

217.᝞cHᙠABCH஺TAB8:HETBC8:HBCD=4BDC.(1)}NBCD=70஺H"1BCḄuᦪ*(2)4EAB+Z.AEB=2BDC.18.“Ḅᑁ.X஺=(n-2)x180஺.পᵬH஺360°*H஺630஺.ᵬஹḄ1ᔩ}1H<ᦪ¡}¢1H£ᳮᵫ*(2)}஻¦T(n+%)HG§ᑁ.X¨¡©360஺Hᵨᑡq«Ḅq¬X.19.®¯H°±°±8E.Ḅ8,ᑁ.fig,ᑁ.Ḅpᑖ2ᡠᜳḄ³.´µᨵ¶·ᐵ¹᝞cপHᙠAADCHDPஹCPᑖSpᑖ4DCX“CD,°±”f4Ḅᦪ»ᐵ¹.°±¼}=AADCᦋT¾¿A8CCᕖÁ᝞c(2),ᙠABCOHDPஹCPᑖiIÂpᑖNADCX4BCD,ᑭᵨÄÅÆ°±NPf4+NBḄᦪ»ᐵ¹.(ᑏ<ᳮÉ«)°±E}=⚪ḄABCCᦋTF4BCDEF(c(3))ᕖÌVÍᑏ

3ÏᫀXÑ᪆1.ூÏᫀ௃BூÑ᪆௃Ñজᔜ()v¬Ḅ*ঝᔜ,ᑁ.()v¬Ḅ*ঞᔜᩩ1.2¢8()HᩭḄv┯ØḄ*টᔜ,᜜.()v¬Ḅ*ঠ78,⚔:;<Ḅ1.2=nᑖᡂ☢A¢8()Ḅ(n-2),E.HᩭḄv┯ØḄ.ᡠJḄᱯ#Ḅᨵ3,.ᦑ⌱B.᪷ßḄàHIáÏᫀ.â⚪ὃã©Hᔜ'()Hᔜ.'()ḄvHä¿8,஻(n>3)ᨵ஻ᩩH”,ᑁ.H1n(n—3)ᩩ1.2.2.ூÏᫀ௃CூÑ᪆௃ூᑖ᪆௃â⚪ὃãḄ1.2èᑖᒘᡂE.,ᦪḄê⚪HÑÏëì⚪íIJVÍîï8,“8,⚔:

4⚪⌕ὃḄឋḄᵨ⚪!"#$%&'()*ᑁ┯()*.4.ூ/ᫀ௃Dூ᪆௃•••3456Ḅ78ᑁ(9108஺3;6Ḅᑁ(990஺Za=360°-108°-2x90°=72°,ᦑ⌱D.<=3456>?3;6Ḅᑁ(Ḅ@ᦪBCDᓽFGHIJ.⚪⌕ὃK56Ḅᑁ(ᐵMNOP3456>?3;6Ḅᑁ(Ḅ@ᦪ.5.ூ/ᫀ௃Aூ᪆௃ூᑖ᪆௃⚪ὃK56ᑁ(RSᳮ.᪷=K56Ḅᑁ(RSᳮV5ᦪḄW⚪XF>Yᓄ9;[ḄW⚪ᩭ].&!ὃK56ᑁ(^᜜(Ḅᐵ`.ab8K56N஻56dḄᑁ(RF>⊤fᡂ(n-2)•180஺XGᑮᐵi஻Ḅ;[VH5ᦪn.ᯠk᪷=K56Ḅ᜜(RN360஺K56Ḅ78ᑁ(l)*ᓽ78᜜(m)*b᪵XoVHK56Ḅp8᜜(.ூ/௃ab8K56N஻56᪷=⚪#G:(n-2)-1800=1800°,Gn=12rstb8K56Ḅp8᜜(N360஺+12=30஺ᓽb8K56Ḅp8᜜(N30஺.ᦑ⌱A.6.ூ/ᫀ௃Aூ᪆௃ூᑖ᪆௃⚪ὃK56Ḅᑁ(^᜜(>?v⊡(⚪ḄᐵMN᪷=K56Ḅ᜜(R9360஺GHBOM=140°.ᙠᓽyz{|p}᪷=K56Ḅ᜜(R9360஺FGHNBOM=140஺~᪷=v⊡(⊡ᓽFGHIJ.ூ/௃ᙠEOyz{|p}M,᝞ᡠfA9456AOEFGḄ᜜(R9360°,

5ᡠ>NBOM=360°-220°=140°,
BOD+BOM=180°,ᡠ>NB஺஺=180°-BOM=180°-140°=40°.ᦑ⌱A.7.ூ/ᫀ௃DᑗḄজ⚔}ᑣᩭ5ᦪK1,ঝp8⚔}ᑣRᩭ5ᦪ)*ঞᢥ᯿⚔}ᑣᩭḄ5ᦪ1,aᑁ(R9720஺ḄK56Ḅ5ᦪNn,ᑣ5-2)-180=720,Gn=6.ᑣK56Ḅ5ᦪ95ᡈ6ᡈ7.ᦑ⌱D.✌ᐜVGᑁ(R9720஺ḄK56Ḅ5ᦪᓽFSK56Ḅ5ᦪ.⚪ὃK56Ḅᑁ(RSᳮᳮᑖNᐵM.8.ூ/ᫀ௃Dூ᪆௃ூᑖ᪆௃⚪ὃ(6Ḅᑁ(R56ᑁ(R]⚪ḄᐵMNᑭᵨ(6Ḅᑁ(R9180஺,n56Ḅᑁ(R9360஺ᑖ⊤fH¡4,B,NC.ᑭᵨ(6Ḅᑁ(R9180஺56Ḅᑁ(R9360஺,ᑖ⊤fHN4/B/C,᪷=¡4=NB=zC,

6G¢Ij/AOE=^NEDC,=/.ADE+AEDC=^EDC+/-EDC=^EDC,ᡠ>஽ADE=l^ADC,ᓽF/.ூ/௃᝞ᙠA/IE஺¤/.AED=60°,஻=180°-NAED-/.ADE=120஺-^ADE,ᙠ56DEBC¤4DEB=180°-/.AED=180°-60°=120°,•••NB=NC=(360°-DEB-"DC)+2=120°-jzEDC,••Z.A=Z-B—zC,120°-Z.ADE=120°-¥EDC,2■■■^ADE=-/.EDC,213••Z.ADC=AADE+EDC=-LEDC+EDC=஽EDC,22./.ADE=-Z.ADC,3ᦑ⌱D.9.ூ/ᫀ௃36ூ᪆௃஻/5C,DE//GF,4B=N¦=72°,•••4DCE=/B=72°,4DEC=zF=72",ᙠ4CDE¤AD=180°-4DCE-DEC=180°-72°-72°=36°.ᦑ/ᫀ936.᪷=$%&'()*FGNDCE=NB,DEC=d,~ᑭᵨ(6Ḅᑁ(RSᳮᑡ¨CDᓽFG.⚪ὃ$%&'()*Ḅឋ(6Ḅᑁ(RSᳮN©Ạ⚪«¬ឋ^SᳮN⚪ḄᐵM.10.ூ/ᫀ௃9ூ᪆௃ூᑖ᪆௃⚪ὃK56ᑭᵨK56Ḅᑁ(RN⚪ᐵM.᪷=K56Ḅᑁ(R¨FG/ᫀ.

7ூ/௃aK569஻56ᵫ⚪#G(n-2)-180°=140°n,Gn=9,ᦑ/ᫀ99.11.ூ/ᫀ௃27ᩩூ᪆௃ூᑖ᪆௃·⚪⌕ὃK56Ḅᑁ(RCD¨VK56Ḅ5ᦪᐵMNOPK56Ḅᑁ(R¨180°(n-2).✌ᐜ᪷=K56ᑁ(R¨FGK56Ḅ5ᦪ~CDH¸(Ḅᩩᦪ.ூ/௃ᵫ⚪#G(n-2)x180=1260,Gn=9,»b8K56Ḅ¸(ᩩᦪ*=27,ᦑ/ᫀ927ᩩ.12.ூ/ᫀ௃540°ூ᪆௃K56Ḅ5ᦪ360஺+72஺=5,3K56Ḅᑁ(RḄ@ᦪN(5-2”180஺=540஺.ᦑ/ᫀ9540஺.᪷=½¾K56Ḅ᜜(RlN360஺ᑭᵨ360◀>᜜(Ḅ@ᦪXF>VH᜜(R¤᜜(Ḅ8ᦪᓽK56Ḅ5ᦪ."56Ḅᑁ(RN(Á-2)•180஺ÂKÃ6Ḅ5ᦪÄᐭ¨XGᑮK56Ḅᑁ(R.ὃK56ᑁ(^᜜(᪷=᜜(RḄᜧÇ^K56Ḅ5ᦪÈᐵᵫ᜜(RV3K56Ḅ5ᦪNÉÊḄ⚪Ë◤⌕«ÍOP.13.ூ/ᫀ௃360°

8ூ᪆௃᝞,vz7=z4+z.6,z8=zl+z5,42+43+47+48=360°,z.1+z.2+z.3+z.4+z.5+z.6=360°.ᦑ/ᫀ9360°.᪷=(6᜜(ឋGᑮ¡7=44+46,Z8=Z1+Z5,᪷=56ᑁ(RᓽFG.·⚪ὃK56Ḅᑁ(ஹ(6᜜(ឋ«¬(6᜜(ឋ?56Ḅᑁ(RN⚪ḄᐵM.14.ூ/ᫀ௃240ூ᪆௃3(6Ḅp8ᑁ(Ḅ@ᦪ9Ò*Ò=60஺356Ḅp8ᑁ(Ḅ@ᦪ9(I)/஺஺=go஺,3456Ḅp8ᑁ(Ḅ@ᦪ9×Ø£=108஺3Ú56Ḅp8ᑁ(Ḅ@ᦪ9(6-2)௃80஺=120஺,6Z1=120°-108°=12°,42=108°-90°=18°,Z.3=90°-60°=30°,43+41—42=30°+12°-18°=24°,ᦑ/ᫀ924஺.ᑖVH3(6ஹ356ஹ3456ஹ3Ú56Ḅᑁ(Ḅ@ᦪIᔠ6CDGᑮ/ᫀ.⚪ὃḄN3K56Rᙊ«¬3K56Ḅᑁ(ḄCD;ÞN⚪ḄᐵM.15.ூ/ᫀ௃aK56Ḅ5ᦪ9ÇFG(n-2)-180°=360°+540°,Gn=7.ᦑb8K56Ḅ5ᦪ97.ூ᪆௃·⚪ßà⌕IᔠK56Ḅᑁ(R¨^᜜(RḄᐵ`ᩭáV*âᐵ`᪀ä;[ᓽFV.⚪ὃK56Ḅᑁ(R^᜜(Rஹ;[Ḅåæ.ᐵMN¬çᑁ(RḄ¨^᜜(RḄᱯé.

916.ூ/ᫀ௃•••456ABCCEḄᔜ8ᑁ(l)*,•••4CDE=(5-2)X180°4-5=108°.•••Z.GDF=70°,•••56ABOE¤4BD=360°-70°-108°-108°=74°,A^ABF=180°-4ABD=180--74°=106°.ூ᪆௃<=456A8CDEḄᔜ8ᑁ(l)*ᓽFGᑮNCDEḄ@ᦪr~᪷=56ᑁ(RᓽFGᑮ448஺Ḅ@ᦪBóGH஻BFḄ@ᦪ.⚪⌕ὃK56Ḅᑁ(RᐵMNOPK56ᑁ(RCD¨.17.ூ/ᫀ௃(1)BCD=BDC=70஺4ABC=180°pBCD-BDC=40°.(2)ôõvZ.EAB+/.AEB+Z.ABE=180°,/.ABC+/.BCD+Z.BDC=180\Z.EAB+Z.AEB=BCD+Z.BDC.÷•••4BCD=BDC,•••Z.EAB+Z.AEB=2/.BDC.ூ᪆௃পᵫNBCD=NBDC=70஺ᑭᵨ(6ᑁ(RSᳮᓽFVHN4BCḄ@ᦪr(2)᪷=(6ᑁ(RSᳮFGHZE4B+4AEB+Z.ABE=180஺ஹZ.ABC+BCD+BDC=180",BóFGHNE4B+AEB=BCD+BDC,~᪷=NBC஺=4BDCᓽùúôHNE4B+^AEB=2BDC.⚪ὃ(6ᑁ(RSᳮ⚪ḄᐵMN(1)ᝅᵨ(6ᑁ(RSᳮVH4ABeḄ@ᦪr(2)ᑭᵨ(6ᑁ(RSᳮ|HNE4B+AAEB=BCD+BDC.18.ூ/ᫀ௃(1)•••36ᫀ+1800=2,630°+180°=3-90°,•••ᵬḄþÞ¸¡ḄþÞ¸360°+180°+2=2+2=4./ᵬ&ÿḄᦪ஻4(2)⚪ᨵ(n+x-2)x1800-(n-2)x180°=360°,x=2.ᦑxḄ2.ூ᪆௃(1)᪷%&'ᑁ)*+,-"'Ḅᑁ)*180°Ḅ/ᦪ01ᓽ-ᑨ405᪷%&'ᑁ)*+,ᓽ-67ᦪ8

10(2)᪷%9:ᐵ<=>஻'?@(n+x)'0ᑁ)*ABC360஺01ᑡ7FG0FGᓽ-HIᐝ.ὃLC&'ᑁ)M᜜)01⚪◤⌕Qᔠ&'Ḅᑁ)*+,ᩭT69:ᐵ<0᪀VFGᓽ-6.19.ூXᫀ௃zP=i(z4+zB+zF+zF)-180°ூ᪆௃=_`a=•£)dஹCPᑖh1Jjᑖk4DC*4ACD,ZPDC=-Z.ADC,/.PCD=-Z.ACD,22DPC=180°-PDC-PCD,=--Z.ADC--Z.ACD,22=180஺-(N4DC+N4CD),=180஺ap180஺ak4),=90°+ᓃ2_`r=•:DPஹCPᑖhItjᑖ4ADC*NBCD,Z.PDC=-Z.ADC,/.PCD=-Z.BCD,22:.DPC=180°a(PDC-PCD,=180஺—LDC-N/BCD,22=180°-=("DC+NBCD),=180஺-“360஺-44aভ0=*+4B)_`z={'A8CDEFḄᑁ)*@=(6-2)•180஺=720஺0,:DPஹCPᑖ~jᑖNEDC*NBC஺0:.PDC=EDC,PCDBCD,22•P=180°-PDC-PCD,11=180°--zEDC--zBCD,221=180஺a(k+k4஺஺)01=180°—(720°—k4a4B-NE-NF),1=,4+k8+4E+ZF)-180°,ᓽNP=+NB+NE+ZF)-180°.

11_`a=᪷%)jᑖḄI-NPDC=)/WC,APCD=^ACD,ᯠ᪷%z)'ᑁ)*Iᳮᑡ,᦮ᳮᓽ-_`r=᪷%'Ḅᑁ)*Iᳮ⊤7k40C+/BCD,ᯠᳮ_`rXᓽ-_`z=᪷%{'Ḅᑁ)*+,⊤74EDC+NBCD,ᯠᳮ_`rXᓽ-.⚪ὃLCz)'Ḅ᜜)ឋ0z)'Ḅᑁ)*Iᳮ0&'Ḅᑁ)*+,01⚪᪷%aX6⚪Ḅᐵ.