宝山区如图,在直角坐标系中,已知直线y=12x+4与y轴交于A点,与x轴交于B点,C点坐标为(-2,0).(1)求经过A,B,C三点的抛物线的解析式;(2)如果M为抛物线的顶点,联结AM、BM,求四边形AOBM的面积.长宁区21.(本题满分10分,第(1)小题5分,第(2)小题5分)如图,点C在⊙O上,联结CO并延长交弦AB于点D,ACBC,联结AC、OB,若CD=40,520AC.(1)求弦AB的长;(2)求ABOsin的值.崇明区21.(本题满分10分,每小题各5分)如图,CD为⊙O的直径,CDAB,垂足为点F,AOBC,垂足为点E,2CE.(1)求AB的长;(2)求⊙O的半径.第21题图DAOBC(第21题图)ABCOFED奉贤区已知:如图,在Rt△ABC中,∠ACB=90°,3BC,2cot2=ABC,点D是AC的中点.(1)求线段BD的长;(2)点E在边AB上,且CE=CB,求△ACE的面积.虹口区黄浦区如图,在△ABC中,∠ACB=90°,AC=4,BC=3,D是边AC的中点,CE⊥BD交AB于点E.(1)求tan∠ACE的值;(2)求AE∶EB.ABCE第21题图DEDCBA嘉定区如图5,在Rt△ABC中,∠C=90°,AC=,BC=2,以点C为圆心,CA长为半径的⊙C与边AB交于点D,以点B为圆心,BD长为半径的⊙B与⊙C的另一个交点为点E.(1)求AD的长.(2)求DE的长金山21.(本题满分10分)如图,已知AB是⊙O的弦,C是AB的中点,AB=8,AC=25,求⊙O半径的长.静安区21.(本题满分10分,其中第(1)小题4分,第(2)小题6分)已知:二次函数图像的顶点坐标是(3,5),且抛物线经过点A(1,3).(1)求此抛物线的表达式;(2)如果点A关于该抛物线对称轴的对称点是B点,且抛物线与y轴的交点是C点,求△ABC的面积.闵行区21.(本题共2小题,每小题5分,满分10分)如图,已知OC是⊙O半径,点P在⊙O的直径BA的延长线上,且OC⊥PC,垂足为C.弦CD垂直平分半径AO,垂足为E,PA=6.求:(1)⊙O的半径;(2)求弦CD的长.浦东新区55(第21题图)ABDCEPOABHFCGDM21.(本题满分10分,其中第(1)小题4分,第(2)小题6分)如图,已知G、H分别是□ABCD对边AD、BC上的点,直线GH分别交BA和DC的延长线于点E、F.(1)当81CDGHCFHSS四边形时,求DGCH的值;(2)联结BD交EF于点M,求证:MGMEMFMH.普陀区21.(本题满分10分)如图8,已知⊙O经过△ABC的顶点A、B,交边BC于点D,点A恰为BD的中点,且8BD,9AC,1sin3C,求⊙O的半径.青浦区21.(本题满分10分,第(1)小题5分,第(2)小题5分)如图6,在平面直角坐标系xOy中,直线)0(kbkxy与双曲线xy6相交于点A(m,6)和点B(-3,n),直线AB与y轴交于点C.(1)求直线AB的表达式;(2)求:ACCB的值.松江区图8ABCDO图6xyOABC21.(本题满分10分,每小题各5分)如图,已知△ABC中,25ABAC,BC=4.线段AB的垂直平分线DF分别交边AB、AC、BC所在直线于点D、E、F.(1)求线段BF的长;(2)求AE:EC的值.徐汇区22.(本题满分10分)如图,在△ABC中,AB=AC,BC=12,4sin5C,点G是△ABC的重心,线段BG的延长线交边AC于点D,求∠CBD的余弦值.杨浦区参考答案宝山区CBADEF(第21题图)第22题BCADG长宁区21.(本题满分10分,第(1)小题5分,第(2)小题5分)解:(1)∵CD过圆心O,ACBC∴CD⊥AB,AB=2AD=2BD(2分)∵CD=40,520AC又∵∠ADC=90∴2022CDACAD(2分)∴AB=2AD=40(1分)(2)设圆O的半径为r,则OD=40-r(1分)∵BD=AD=20,∠ODB=90∴222OBODBD∴222)40(20rr(1分)∴r=25,OD=15(2分)∴532515sinOBODABO(1分)崇明区21、(1)∵CDAB,AOBC∴90AFOCEO∠∠………………………………………1分在AOFCOE△和△中AFOCEOAOFCOEAOCO∠∠∠∠∴AOFCOE△≌△……………………………………………1分∴CEAF………………………………………………………1分∵2CE∴2AF∵CD是O的直径,CDAB∴12AFBFAB……………………………………………1分∴4AB…………………………………………………………1分(2)∵AO是O的半径,AOBC∴2CEBE………………………………………………1分∵4AB∴12BEAB∵90AEB∠∴30A∠……………………2分又∵90AFO∠∴232AFCosAAOAO…………1分∴433AO即O的半径是433………………………1分奉贤区虹口区黄浦区21.解:(1)由∠ACB=90°,CE⊥BD,得∠ACE=∠CBD.———————————————————————(2分)在△BCD中,BC=3,CD=12AC=2,∠BCD=90°,得tan∠CBD=23,———————————————————————(2分)即tan∠ACE=23.———————————————————————(1分)(2)过A作AC的垂线交CE的延长线于P,—————————————(1分)则在△CAP中,CA=4,∠CAP=90°,tan∠ACP=23,得AP=28433,——————————————————————(2分)又∠ACB=90°,∠CAP=90°,得BC∥AP,得AE∶EB=AP∶BC=8∶9.—————————————————(2分)嘉定区如图5,在Rt△ABC中,∠C=90°,AC=,BC=2,以点C为圆心,CA长为半径的⊙C与边AB交于点D,以点B为圆心,BD长为半径的⊙B与⊙C的另一个交点为点E.(1)求AD的长.(2)求DE的长【评析】(1)由∠C=90°,可得AB=5.作CF⊥AB,由题可知△ACB∽△CFB,,得CF=2,又得AF=1,所以AD=2(2)设DE与CB交于点G,由AD=2得BD=3,由△ACB∽△DGB得DG=,所以DE=金山55静安区21.解:(1)∵二次函数图像的顶点坐标是(3,5),∴设二次函数的解析式为…………………………………(2分)又∵抛物线经过点A(1,3),代入解析式解得:21a……(1分)∴此二次函数的解析式为5)3(212xy,即213212xxy……(1分)(2)∵B点是点A关于该抛物线对称轴的对称点,∴B(5,3),AB=5-1=4,……(2分)∵2132122xxy与y轴的交点是C点,∴C(0,),25213h……(2分)∴△ABC的面积=525421………………………………………………(2分)闵行区21.解:(1)∵OC⊥PC,∴∠PCO=90°.∵弦CD垂直平分半径AO,∴OE=EA,∠CEO=90°.…………………(1分)∴∠PCO=∠CEO.…………………………………………………………(1分)又∵∠COE=∠COE,∴△OCE∽△OPC.…………………………………(1分)∴OEOCOCOP.………………………………………………………………(1分)又∵PA=6,∴OC=6.即:⊙O半径为6.………………………………(1分)(2)∵1122EOAEAOCO,∠CEO=90°,∴∠OCE=30°,222OECECO.………………………………………(2分)∵OC=6,∴OE=3,CE=33.…………………………………………(1分)∵OA过圆心,OA⊥CD,∴2263CDCEED.………………………………………………(2分)浦东新区21.(1)解:∵81CDGHCFHSS四边形,∴91DFGCFHSS.……………………………………………………(1分)∵□ABCD中,AD//BC,∴△CFH∽△DFG.………………………………………………(1分)∴91)(2DGCHSSDFGCFH.……………………………………………(1分)∴31DGCH.…………………………………………………………(1分)(2)证明:∵□ABCD中,AD//BC,∴MGMHMDMB.……………………………………(2分)∵□ABCD中,AB//CD,215)3(2xay5)31(32a∴MDMBMFME.……………………………………(2分)∴MGMHMFME.……………………………………(1分)∴MHMFMEMG.……………………………(1分)普陀区20.解:联结OA、交BC于点H,联结OB.·····································································(1分)∵点A为BD的中点,OA是半径,8BD,∴AHBC,142BHBD.··············································································(3分)在Rt△AHC中,90AHC,9AC∴1sin93AHAHCAC,得3AH.···································································(2分)设⊙O的半径为x.在Rt△BHO中,由勾股定理,得222BHHOBO,即2224(3)xx.··································································································(2分)解得256x.∴⊙O的半径为256.·································································································(2分)青浦区21.解:(1)∵点A(m,6)和点B(-3,n)在双曲线xy6,∴m=1,n=-2.∴点A(1,6),点B(-3,-2).………………………………………………………(2分)将点A、B代入直线ykxb,得=632.;kbkb解得=24.;kb…………………(2分)∴直线AB的表达式为:24yx.…………………………………………………(1分)(2)分别过点A、B作AM⊥y轴,BN⊥y轴,垂足分别为点M、N.……………………(1分)则∠AMO=∠BNO=90°,AM=1,BN=3,……………………………………………(1分)∴AM//BN,………………………………………………………………………………(1分)∴1=3ACAMCBBN.…………………………………………………………………………(2分)松江区21.解:过A点作AH⊥BC于点H………………1分∵25ABAC,BC=4.∴BH=CH=2,AH=4……………………………2分∴55cosB…………………………………1分∵DF垂直平分线AB,∴5BD,090BDF∴BF=5……………………………………………………………1分(2)由(1)得CF=BF-BC=5-4=1……………………………1分过点C作CM∥AB………………………………………………1分则AE:EC=AD:CM……………………………………………1分∵AD=BDAE:EC=BD:CM=BF:CF=5:1=5……………………………2分徐汇区22.联结AG交BC于