初中数学最值问题专题

经典word整理文档，仅参考，双击此处可删除页眉页脚。本资料属于网络整理，如有侵权，请联系删除，谢谢！．C．axbxy2DA作ADBMPBCPBCP1QOC＋QC2yC321MAB123xOD练习23x）x233232ABC4和1aBP上22．1xxy与x第1xxxx与xR50030x，P1702x。是222xyym5，xyymmx3mxABCD从BBAAD与AD作BC交ACDAEyxxxBDESABCQBCMBM作BCACBQ为．xQBMABC；BMNQax2bxcy3DEPPC，记旋转角为90180，与．DADBCE15交．BCF①写出旋转角ADAB2P11＝c＝，B22xlP为yP作PA交yPQABCP4Bax2bxc(a0)，，ABCyPDACDAC与xyCcx．xEDECEDAPBOCBP52xyyyyPx112121C作xx、FCBNCD和CEFMN•ABCBC在xABCAxcyP2P从AB1BtP作AB交ACDyltACQMxCM6．C．7．=，．axbxy2DA作ADBMPBCPBCP8QOC＋QCyC321MAB-21-123xO-1DCcAMBDP作ABBCmBCx2PEmmSSSPEOB22＝mSP21tCQ为GQ2QGQAAQ＋QAQ＝tax2x2x22Dx29DBADBMDAM，ADBMyC321MA12xODP作ABBCmBC2mm．22yyCC332G2E1M1QA1BFAB-12xO-121xO33PDD图2图3SSS＝•＋•＝•＝m)22＝SPPBC△1CQ＋＝t2取CQQQGQA＋Q＝＋QC．x）ABC4和4a12bchabcabb12bch得12b4bhh3a22abbaba2222332222224b10当a，b2BP上．．A=A，，即2．1xxy与x第1xxxx2)2a)2xx12当当xx22y与x＝2x当y当xy22a2x与xR50030x，P1702x。2x)x30x)1750x270x1125025x45x，12PxR2x140x5002(x195022x35是xx)150x2x0x50y600xx)400x1500000x50（）yy随x50ymin130000xxx22x1x1。x0xyyxx22x1x1y设即xy)y)0即2213y3xx2x1x1。21x2xx1x211xsin，y，x221yx1x1cos2222yy|x|x5yy、4当x时y(x(x4)50当4x1时4当x10y2x801y(x(x4)510当x4xym5，xyymmx3m33(xy)3)m2m322213m3ABCD从BBAAD与A2D作BC交ACDAEyxxxBDESABCADEDx．．，∴∴，，yx＝＝＝当Scm．2ABCQBCMBM作BCACBQ为．xQBMABC；BMNQ，MQBMQBCABQBMABC，QBMABC；当MNBMNQ，BMNQBCxQBMABC，∴＝＝＝＝，＝＝，，∴＝，BMNQ﹣+＝，，＝BMNQ．DEPPBC与x或EPx2xx的P把22C取==，．或5:3，11令2S作2x－22x21x－22x432ABCBAC90ABCC，记旋转角为90180，与．DADBCE15交．BCF①写出旋转角；2P段交CAOEMECCMFCM△(A2，，交AFBMACACMAA△，，BF105．1，CD75，，旋转角为105．AF交CAOCEDCEE451560，，CEA，FCO180457560，，，，，COE，COE∽，AOFCFF，，CEM60，CEMECM60，CMCE，，FCMCE，)，E，2，，交AF，，，A△，，，FE，，在△1M1，22222626．＝+c＝BxlP为yP作PA交yPQABCP＝x2MM＝xc2，＝x+2＝AMBCB作xBEC＝；PQABC在BECBCE在ACOACOACB，000P作PAAPQP作yPQAAPQPAGQAPPGAQPAPGAACB，PAGBAC，∴xx12P+2PPAGABC，∴，xx12PByaxbxc(a0)2PDACDACOAOCOB4((23yaxxaxx22、、；AC((23，x即441，aayx3x4；2y4，Ckyx4，P作yAC4，轴，PHDOCA45，22(x4x3x22x，x222222P与xyCcx．xEDECEDAPBOCBP与xyCCCCxxEDP在xP在x与xyCCC，令或CxCDxED将CDCD当x（P在xOCBAPB，B作，，22m）m则PB，则y；PP在x则yPPaxc过2xyyyyPx112121C作xx、FCBNCD和CEFMNy2当yy时Px121F是BCFFCECEaxc过2∴＝；＝+yy）22xyyy12x或x1