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    2022年三角形四心的向量性质及应用20120516 .pdf

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    2022年三角形四心的向量性质及应用20120516 .pdf

    -1-三角形“四心”的向量性质及其应用三角形“四心”的概念介绍(1)重心三条中线的交点:重心将中线长度分成2:1;(2)外心三边中垂线的交点(外接圆的圆心):外心到三角形各顶点的距离相等;(3)垂心三条高线的交点:高线与对应边垂直;(4)内心三条内角平分线的交点(内切圆的圆心):角平分线上的任意点到角两边的距离相等工具:O为ABC内一点,则有:0OCSOBSOASOABOCAOBC证明:延长AO交BC于D,如图必有:|OAODSSSOABOCAOBC,|BCBDSSSOABOCAOAB,|BCCDSSSOABOCAOCA;-(*)由DOA,共线,得:0|ODODOAOA进而得:0|ODOAOAOD -由CDB,共线,得:OCBCBDOBBCCDOD|-由得:OAOAOD|0|OCBCBDOBBCCD代入(*)结论得OASSSOABOCAOBCOBSSSOABOCAOCA0OCSSSOABOCAOAB消去分母得:0OCSOBSOASOABOCAOBC证毕.另证:作ACOGABOH/,/,如图:AGOH为平行四边形;由OCSOBSOASOABOCAOBC)()(ACOASABOASOASOABOCAOBCACSABSOASOABOCAABC)(ACSSABSSOASABCOABABCOCAABC)(ACACAHABABAGOASABC)(AHAGOASABC0)(AOOASABCABCODABCODHFEG-2-反方向思考:设O在ABC的内部,若有正实数321,满足:0321OCOBOA,必有:AOBCOABOCSSS:321证明:作:OAOA1,OBOB2,OCOC3则OAOB0OC,则O为CBA的重心,则:OBAOACOCBSSS.设为S又SSSSSSSSSAOBOBACOAOACBOCOCB2!1332从而得:AOBCOABOCSSSSSS:211332321验证式思考:先证引理:若ba,不共线,对p,有0pa且0pb,必有.0p证明:若.0p必有pa且pb,得ba/,与题设矛盾,故必有.0p再证:设BOC,COA,则2AOB;由)(OCSOBSOASOAOABOCAOBCOCOASOBOASOASOABOCAOBC2cos)2sin(21)2cos(sin21sin212OCOAOBOAOBOAOAOCOAOCOBcos)sin()cos(sinsin212OCOBOA)(sinsin212OCOBOA0)sin(sin212OCOBOA;有对称性知:0)(OCSOBSOASOBOABOCAOBC,又OA,OB不共线,故:必有0OCSOBSOASOABOCAOBC成立一、三角形的重心的向量表示及应用知识:G 是ABC的重心)(31ACABAG0GCGBGA)(31OCOBOAOG (O为该平面上任意一点)略证:1:1:1:GABGCAGBCSSS,得:0GCGBGA变式:已知 DEF,分别为ABC的边 BCACAB,的中点则0CFBEAD二、三角形的外心的向量表示及应用知识:O是ABC的外心222|OCOBOAOCOBOAABCOABCABCO文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8-3-02sin2sin2sinOCCOBBOAA略证:CBASSSOABOCAOBC2sin:2sin:2sin:,得:02sin2sin2sinOCCOBBOAA常用结论:O是ABC的外心.2|;2|22ACAOACABAOAB三、三角形的垂心的向量表示及应用知识:H是ABC的垂心HAHCHCHBHBHA222222|ABHCCAHBBCHA0tantantanHCCHBBHAA略证:CBASSSHABHCAHBCtan:tan:tan:,得:0tantantanHCCHBBHAA扩展:若O是ABC的外心,点H满足:OCOBOAOH,则H是ABC的垂心证明:如图:BE为直径,H为垂心,O为外心,D为BC中点;有:为平行四边形AHCEEACHABEAABCHECAHBCECBCAH/进而得到:,/ECAH且ECAH,即:ECAH;又易知:OCOBODEC2;故:OAOHOCOBAH,即:OCOBOAOH又:OGOCOBOA3(G为重心),故:OGOH3;故:得到欧拉线:ABC的外心O,重心G,垂心H三点共线(欧拉线),且GHOG21证毕四、三角形的内心的向量表示及应用知识:I是ABC的内心0|0|0|CBCBCACACIBCBCBABABIACACABABAI0|0|0|CACABCBCCIBABACBCBBIACACBABAAI0ICcIBbIAacbaOCcOBbOAaOI0sinsinsinICCIBBIAA注:式子中|,|,|ABcCAbBCa,O为任一点ABDOHCE文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8-4-略证:CBAcbaSSSIABICAIBCsin:sin:sin:,得之五欧拉线:ABC的外心O,重心G,垂心H三点共线(欧拉线),且GHOG21(前已证)测试题一选择题1O是ABC所在平面上一定点,动点P满足)(ACABOAOP,,0,则点P的轨迹一定通过ABC的()A外心B内心C重心D垂心2(03 全国理 4)O是ABC所在平面上一定点,动点P满足)(ACACABABOAOP,,0,则点P的轨迹一定通过ABC的()A外心B内心C重心D垂心3O是ABC所在平面上一定点,动点P满足)coscos(CACACBABABOAOP,R,则点P的轨迹一定通过ABC的()A外心B内心C重心D垂心4O是ABC所在平面上一定点,动点P满足)sinsin(CACACBABABOAOP,,0,则点P的轨迹一定通过ABC的()A外心B内心C重心D垂心5O是ABC所在平面上一定点,动点P满足2coscosOBOCABACOPABBACC,R,则点P的轨迹一定通过ABC的()A外心B内心C重心D垂心6O是ABC所在平面上一定点,动点P满足)21()1()1(31OCOBOAOP,*R,则点P的轨迹一定通过ABC的()A内心B垂心C重心DAB 边的中点7已知O是ABC的重心,动点P满足)22121(31OCOBOAOP,则点P一定为ABC的()AAB 边中线的中点BAB 边中线的三等分点(非重心)C重心DAB 边的中点8在ABC中,动点P满足:CPABCBCA222,则P点轨迹一定通过ABC的()外心内心C重心D垂心9已知ABC三个顶点CBA、及平面内一点P,满足0PCPBPA,若实数满足:APACAB,则的值为()A2 B23C3 D6 10设点P是ABC内一点,用ABCS表示ABC的面积,令ABCPBCSS1,ABCPCASS2,ABCPABSS3文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8-5-B C A M N G 定义),()(321Pf,若)61,31,21()(),31,31,31()(QfGf则()A点Q在ABG内B点Q在BCG内C点Q在CAG内D以上皆不对11若ABC的外接圆的圆心为O,半径为1,0OCOBOA,则OBOA()A21B 0 C1 D2112O是平面上一定点,CBA、是平面上不共线的三个点,若222OBBCOA222ABOCCA,则O是ABC的()A外心B内心C重心D垂心13(06 陕西)已知非零向量AB与AC满足0|BCACACABAB且21|ACACABAB,则 ABC 为()A三边均不相等的三角形B直角三角形C等腰非等边三角形D等边三角形14已知ABC三个顶点CBA、,若CABCCBABACABAB2,则ABC为()A等腰三角形B等腰直角三角形C直角三角形D既非等腰又非直角三角形二填空题15ABC的外接圆的圆心为O,两条边上的高的交点为H,)(OCOBOAmOH,则实数m=1 16ABC中,7,3,1BCACAB,O为重心,则ACAO2717点O在ABC内部且满足032OCOBOA,则:ABCSAOCS3 18点O在ABC内部且满足ACABAO5152,则:ABCSAOBS4 19已知ABC中,6,5 BCACAB,I为ABC的内心,且BCABAI,则1615.20已知ABC中,1,1,2ACABACAB,O为ABC的外心,且BCyABxAO,则yx2721已知O为锐角ABC的外心,30A,若AOmBCACCBAB2sincossincos,则m2122在ABC中,1,3,ADBDBCABAD,则ADAC3三解答题23 如图,已知点G是ABC的重心,过G作直线与ACAB,两边分别交于NM,两点,且AMxAB,ANyAC,求证:113xy解:由NGM,三点共线,得:ANtAMtAG)1(ACtyABxt)1(-又G是ABC的重心文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8-6-得:ACABAG3131 -由得:3131)1(tyxt,消去t得:113xy.24设O在ABC的内部,若有正实数321,满足:0321OCOBOA,求证:AOBCOABOCSSS:321证明:作:OAOA1,OBOB2,OCOC3则OAOB0OC,则O为CBA的重心,则:OBAOACOCBSSS.设为S又SSSSSSSSSAOBOBACOAOACBOCOCB2!1332从而得:AOBCOABOCSSSSSS:21133232125已知向量1OP,2OP,3OP 满足条件1OP+2OP+3OP=0,|1OP|=|2OP|=|3OP|=1,求证:321PPP为正三角形证明:由1OP+2OP+3OP=01OP+2OP=3OP平方得:1212112121OPOPOPOP从而得:3211)(|2121222121OPOPOPOPPPPP同理可得:3|1332PPPP,即321PPP为正三角形26在ABC中,60,5,2AACAB,求从顶点BA,出发的两条中线BEAD,的夹角的余弦值解:设bABaAC,,则,560cos25,4,2522baba且baBEbaAD21),(21;则,3)8525(41)2(41)21()(2122bbaababaBEAD2394102521221|)(|21|22bbaabaAD221162025214421|)2(|21|22bbaabaBE故:.919149142212393|,cosBEADBEADBEADABCOABCABEDC文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8-7-27已知H是ABC的垂心,且|BCAH,试求A的度数解:设ABC的外接圆半径为R,点O是ABC的外心。H是ABC的垂心OCOBOAOHOCOBOAOHAH,AOCOB2,)2cos1(2)(|2222AROCOBAHAHOBOCBC,)2cos1(2)(|2222AROBOCBCBC|BCAH,AA2cos12cos102cos A而A为ABC的内角,36020A从而902A或2702AA的度数为45或135.28已知),(),0,1(),0,0(cbCBO,试写出OBC的重心G,外心F,和垂心H的坐标,并证明HFG,三点共线(2002 全国)解:易知)3,31(cbG;设),(0ybH,由BCOH,且),1(),(0cbBCybOH,得0)1(),1(),(00cybbcbybBCOH,得cbby)1(0,即)1(,(cbbbH;设),21(yF,则由cbcbycybyFCFO2)()21(41|22222,即)2,21(22cbcbF.而且:)233,212(),633,612(2222ccbbbFHccbbbFG易知:FGFH3(又有公共端点F),故HGF,三点共线.29已知G、M分别为不等边ABC的重心与外心,)0,1(A、B)0,1(且GMAB,(1)求点C的轨迹方程;(2)若直线l过点(0,1),并与C的轨迹曲线交于P、Q两点,且满足0OQOP(O为坐标原点),求直线l的方程解:(1)设),(yxC,则)3,3(yxG,再设),0(0yM,由/GMAB,易得:.30yy故外心)3,0(yM;由|MBMC,代入坐标得:91)3()0(222yyyxABCHO文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H5V1 HS5C7Q8Q6D3 ZR9H8V8C9M8文档编码:CY2Y4H6H

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