2022-2023学年安徽淮南寿县八年级数学第一学期期末学业质量监测试题含解析

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2022-2023
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18BCLOQ,•••NCBb=90°,•••NC8A=45°,LᳮZfiAC=45°.ᙠAAOBNZXACBOZOAB=ZCABOA=OB=AC=BCÌ2᝞R1,ᙠSTAPUV-O,WA£>=M,XYCO.pᙠ¬C4ZÍNVCBZOCA=CB

19CD=CF=3E,±²CD.•••ZC4£)=ZCBF=90%ᙠ¬C4Z)VCB/5CA=CB

20EC=EC<4ECD=NECF,CD=CF:.AECDAECF(SAS),.ZD=ZCFM,•••^CAD^NCBF,ZD=/CFB,ZCFM=ZCFB,vAC//OQ,NMCF=NCFB,•••/CFM=ZMCF,MC=MF,LᳮC%CN=EN,ᙠRtAMCN,ᵫ[\]ᳮ^%MN2=CN2+CM2=EN2+FM2.ூ-.௃/⚪4ᔠὃ12ᐰFHIḄឋb:ᑨ][\]ᳮdefIḄᨵᐵhijklmnoT᪀⌼ᐰFHIjkCDᐰFHI^ᑮTstuḄᐵv=⚪ḄᐵA.24ஹ234ூᑖ᪆௃XYAC,᝞Rᐜ᪷y[\]ᳮzAC,ᯠ᪷y[\]ᳮḄ⌮]ᳮ^ND=90°,ᑭᵨS|}~ABCD=SAABC+SAACDzᓽ.ூ௃%XYAC,᝞R•••NB=90஺A8=15,BC=20,AC=y]AB2+BC2=V152+202=25VAD2+CD2=242+72=625,AC2=252=625,.\AD2+CD2=AC2,.••ZD=90°,S|}IABCD=SAABC+SAACD=-x15x20H—x24x7=150+84=234.22

21Aூ-.௃/⚪ὃ12[\]ᳮeᐸ⌮]ᳮE⚪7[\]ᳮeᐸ⌮]ᳮ=⚪ḄᐵA.25ஹ—2-2ᡠdFḄ-2

22180°-120°AZB=ZA=----------------=30°o,2Aa=180°-110o-30o=40°,•NIÎḄ`IgPMÏÐÑ´:C,W¾ÒÓḄ´5NAPN.ÔᜧNAḄMᦪᨵÔᓄ,᪷NIOḄᑁIQᳮSᑮNADP⌲×Ô&ᦑlᫀn:40°,&.(2)4Ç=5APDg/kBCÇ.ᳮᵫ᝞°VVZACB=120o,CA=CB,.*.ZA=ZB=30o.bNAPC8PCḄ2#᜜I,.ZAPC=ZB+a=30°+NPCB,VZAPC=ZDPC+ZAPD=3()°+ZAPD,.ZAPD=ZBCP,AP=BC=5ᙠÇ஺Q8CP5,NA=NB,AP=BCZAPD=NBCP:AAPDBCP(ASA)(3)ḄOØ,¡
ῪNIO.᪷⚪uSVZPCD=120°-a,ZCPD=30°,ᨵ¡°NÙÚÛVজÇC=P஺2Ý)
ῪNIOIQ003f):.NPCD=NPDC=——--=75°,ᓽ120°-a=752.,.a=45°ঝOP=DCPCD
ῪNIO.NPCD=NCPD=30°,ᓽ120°-a=30°,.,.a=90°;ঞCP=C஺PC஺
ῪNIO.,.ZCDP=ZCPD=30°,.,.ZPCD=180°-2X30°=120°,

23ᓽ120°-a=120",.,.a=0°,?¢-ZN-B·ᔠ¸ᔠ⚪¹º».4Uᡠ¼¡a=45°ᡈ90°¢PCD=FῪHI.ூ-.௃/⚪½⌕ὃ12ᐰFHIḄᑨ]ASA
ஹFῪHIḄᑨ]ஹHIḄᑁH:]ᳮ¿HIḄᑁH:=180°À,7ᐰFHIḄᑨ]]ᳮ=⚪ḄᐵA.