第十七届五羊杯初中数学竞赛初二试题

200511901005501423(7)1337986(2)9(8)62−+−−−−+−−−−+−−−−−−−−=A−2B0C−1D12322xyxy−=+2222(32)(3)(4)(22)xyxyxyxy+−−−−+=A39/25B−39/25C39/20D−39/203Aoshoo.com2223xyxy=+392yzyz=−−51537xyzxyyzzx=−+,,xaybzc===222abc++=A1011514455432(2)xaxbxcxdxexf+=+++++164bdf++=A5121024204840965**4ababab×=+−20*20*2005*5*5=A0251562520056n=1201201201202n10A608190997xyxy210022xy+=A2516100042516100048n12mn=mn2nA123491ABCΔ6BC=5AC=BC1D2D3D4D5DAC1E2E3E4E1AD2AD3AD4AD5AD1E2E3E4EBC11EF22EF33EF44EFAB1F2F3F4FA115.5462420308102550FGDEHCABBCAD5D1F1E2F3E42112222111(1)xxABCxxxxx+−=++−−ABCABC++=_____12Aoshoo.com33ABCDPQRSPQRSUVWXUVWX100ABCD_____13n123,,324324324324nLL23n=_____144ABCΔ39A∠=°ABC∠BDBEACB∠CFCGBECGHBHC∠_____15[]xx22221111[23415]23415++++=L_____162(32)3xy−+=2(32)3yz−+=2(32)3zu−+=2(32)3ux−+=x=_____175ABCDE4BC=4CDAB=−6AEDE==AEAB⊥DECD⊥_____18n1515nm=m120n×36n×5n_____196MNDUVBABCD60MNUVDABCAVBMPCNDUQBMCNRAVDUSPQRS24USVΔMRNΔ16APMΔBPVΔCQUΔDQNΔ_____20iAAB∠i∠78123∠=∠+∠8981∠2∠3∠8∠1258∠=∠+∠+∠,,xyz28xyz≤≤≤≤1xyz∠=∠+∠+∠(,,)xyz=__________646DCEABA3A2A1BA8A7A6A5A4A3A2A1BAA