中考数学B卷及答案

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B卷(共50分)一、填空题:(每小题4分,共20分)将答案直接写在该题目中的横线上.1.不等式组52(1)1233xxx,≤的整数解的和是.2.含有4种花色的36张扑克牌的牌面都朝下,每次抽出一张记下花色后再原样放回,洗匀牌后再抽.不断重复上述过程,记录抽到红心的频率为25%,那么其中扑克牌花色是红心的大约有张.3.如图,以等腰三角形ABC的一腰AB为直径的O交BC于点D,交AC于点G,连结AD,并过点D作DEAC,垂足为E.根据以上条件写出三个正确结论(除ABACAOBOABCACB,,∠∠外)是:(1);(2);(3).4.已知某工厂计划经过两年的时间,把某种产品从现在的年产量100万台提高到121万台,那么每年平均增长的百分数是.按此年平均增长率,预计第4年该工厂的年产量应为万台.5.如图,如果以正方形ABCD的对角线AC为边作第二个正方形ACEF,再以对角线AE为边作第三个正方形AEGH,如此下去,….已知正方形ABCD的面积1S为1,按上述方法所作的正方形的面积依次为23nSSS,,,(n为正整数),那么第8个正方形的面积8S.二、(共8分)6.如图,某校九年级3班的一个学习小组进行测量小山高度的实践活动.部分同学在山脚点A测得山腰上一点D的仰角为30,并测得AD的长度为180米;另一部分同学在山顶点B测得山脚点A的俯角为45,山腰点D的俯角为60.请你帮助他们计算出小山的高度BC(计算过程和结果都不取近似值).ABCOGEDICBAHGJFDEACBHD456030三、(共10分)7.已知:如图,O与A相交于CD,两点,AO,分别是两圆的圆心,ABC△内接于O,弦CD交AB于点G,交O的直径AE于点F,连结BD.(1)求证:ACGDBG△∽△;(2)求证:2ACAGAB;(3)若A,O的直径分别为65,15,且:1:4CGCD,求AB和BD的长.8.已知:如图,在正方形ABCD中,12AD,点E是边CD上的动点(点E不与端点CD,重合),AE的垂直平分线FP分别交ADAEBC,,于点FHG,,,交AB的延长线于点P.(1)设(012)DEmm,试用含m的代数式表示FHHG的值;(2)在(1)的条件下,当12FHHG时,求BP的长.四、(共12分)9.如图,在平面直角坐标系中,已知点(220)B,,(0)Am,(20)m,以AB为边在x轴下方作正方形ABCD,点E是线段OD与正方形ABCD的外接圆除点D以外的另一个交点,连结BE与AD相交于点F.(1)求证:BFDO;(2)设直线l是BDO△的边BO的垂直平分线,且与BE相交于点G.若G是BDO△的外心,试求经过BFO,,三点的抛物线的解析表达式;(3)在(2)的条件下,在抛物线上是否存在点P,使该点关于直线BE的对称点在x轴上?AEODCBGFAEHDCBGFP若存在,求出所有这样的点的坐标;若不存在,请说明理由.B卷(共50分)一、填空题:(每小题4分,共20分)21.0;22.9;23.(1)BDDC,(2),(3)DE是O的切线(以及;24.10%,146.41;25.128.RtRtDECADC△∽△BADCADADBCBDDG∠∠,,等)二、(共8分)26.解:如图,过点D作DEAC于点E,作DFBC于点F,则有DEFCDFEC∥,∥.90DEC∠,四边形DECF是矩形,DEFC.·········································2分45HBABAC∠∠,453015BADBACDAE∠∠∠.又604515ABDHBDHBA∠∠∠,ADB△是等腰三角形.180ADBD(米).·························2分在RtAED△中,sinsin30DEDAEAD∠,1180sin30180902DE(米),90FC米.在RtBDF△中,60BDFHBD∠∠,sinsin60BFBDFBD∠,AEODCBGFxylACBHD456030EF3180sin601809032BF(米).903909031BCBFFC(米).答:小山的高度BC为9031米.············································4分三、(共10分)27.(邛崃、大邑、新津、蒲江四市、县考生不做,其余考生做)(1)证明:在ACG△和DBG△中,CAGBDGAGCDGB∠∠,∠∠,ACGDBG△∽△.································································2分(2)证明:连结AD,则ACAD.在ACG△和ABC△中,ACADACGABC,∠∠.又CAGBACACGABC∠∠,△∽△.ACAGABAC,即2ACAGAB.·······················4分(3)解:连结CE,则90ACE∠.O与A相交于CD,两点,圆心OA,在弦CD的垂直平分线上,即AO垂直平分弦CD.CFDFCFAE,且ACAD.AO,的直径分别为65,15,3515ACAE,.在RtCFA△和RtECA△中,ACFADCAEC∠∠∠,RtRtCFAECA△∽△.ACAFAEAC,即2235315ACAFAE.在RtAFC△中,由勾股定理,得222ACAFCF,即222353CF.解得6CF(舍去负值).:1:439CGCDCGFGDG,,.在RtAFG△中,由勾股定理,得222223318AGAFFG,32AG(舍去负值).由(2),有2ACAGAB,即23532AB.解得1522AB.AEODCBGF由(1),有ACGDBG△∽△,得ACAGDBDG.359910232ACDGBDAG.···········································4分27.(邛崃、大邑、新津、蒲江四市、县考生做,其余考生不做)解:(1)过点H作MNAB∥,分别交ADBC,于MN,两点.FP是线段AE的垂直平分线,AHEH.MHDE∥,RtRtAHMAED△∽△.1AMAHMDHE.AMMD,即点M是AD的中点.从而6AMMD.MH是ADE△的中位线,1122MHDEm.四边形ABCD是正方形,四边形ABNM是矩形.12MNAD.1122HNMNMHm.ADBC∥RtRtFMHGNH△∽△,.121122mFHMHGHNHm,即01224FHmmHGm.··················6分(2)过点H作HKAB于点K,则四边形AKHM和四边形KBNH都是矩形.1242FHmHGm,解得8m.1111841212882222MHAKmHNKBm,,6KHAM.RtRtAKHHKP△∽△,KHAKKPHK,即2KHAKKP.又24664AKKHKP,,,解得9KP.981BPKPKB.······················································4分四、(共12分)解:(1)在ABF△和ADO△中,四边形ABCD是正方形,90ABADBAFDAO,∠∠.又ABFADOABFADO∠∠,△≌△,BFDO.···········································································3分(2)由(1)AEHDCBGFPKMN的外,有ABFADO△≌△,AOAFm.点Fmm,.G是BDO△心,点G在DO的垂直平分线上.点B也在DO的垂直平分线上.DBO△为等腰三角形,2BOBDAB.而222222BOABmm,,22222222mm,.222222F,.设经过BFO,,三点的抛物线的解析表达式为20yaxbxca.抛物线过点00O,,0c.2yaxbx.··············①把点220B,,点222222F,的坐标代入①中,得2202222222222222.abab,即2202221.abab,解得122.ab,抛物线的解析表达式为2122yxx.····················②······························································5分(3)假定在抛物线上存在一点P,使点P关于直线BE的对称点P在x轴上.BE是OBD∠的平分线,x轴上的点P关于直线BE的对称点P必在直线BD上,即点P是抛物线与直线BD的交点.设直线BD的解析表达式为ykxb,并设直线BD与y轴交于点Q,则由BOQ△是等腰直角三角形.OQOB.022Q,.把点220B,,点022Q,代入ykxb中,得02222.kbb,122.kb,直线BD的解析表达式为22yx.AEODCBGFxylQ设点00Pxy,,则有0022yx.····························③把③代入②,得200012222xxx,2001212202xx,即200221420xx.002220xx.解得022x或02x.当022x时,02222220yx;当02x时,0022222yx.在抛物线上存在点122202222PP,,,,它们关于直线BE的对称点都在x轴上.·············································································4分

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