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2009年广西桂林市百色市中考数学真题及答案.doc

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2009 年广西桂林市百色市中考数学真题及答案 (考试用时:120 分钟 满分: 120 分) 注意事项: 1.本试卷分选择题和非选择题两部分.在本试卷上作答无效. .......... 2.考试结束后,将本试卷和答题卷一并交回. 3.答题前,请认真阅读答题卷上的注意事项 ............... 一、选择题(共 12 小题,每小题 3 分,共 36 分.在每小题给出的四个选项中只有一项是符合要求的,用 2B 铅笔把答题卷...上对应题目的答案标号涂黑) 1. 8 的相反数是( ). 1 8 A. 8 1 8 2.下面的几个有理数中,最大的数是( B.8 C. D.  A.2 B. 1 3 C.-3 D.  1 5 3.如图,在所标识的角中,同位角是( A. 1 和 2 C. 1 和 4 4.右图是一正四棱锥,它的俯视图是( B. 1 和 3 D. 2 和 3 ). ). ). 1 2 3 4 (第 3 题图) A. B. C. D. (第 4 题图) 5.下列运算正确的是( ). A. 2 a b   2 ab B. (  )ab 2  2 2 a b C. 2a · 2a = 22a D. 4 a 2 a  2 6.二次函数 y ( x  1) 2  的最小值是( 2 ). A.2 2 3 7.右图是一张卡通图,图中两圆的位置关系是( C.-3 B.1 D. ). A.相交 B.外离 C.内切 D.内含 (第 7 题图) 8.已知 x    y 2 1 是二元一次方程组 ax by ax by        7 1 的解,则 a b 的值为( ). A.1 9.有 20 张背面完全一样的卡片,其中 8 张正面印有桂林山水,7 张正面印有百色风光,5 张正面印有北 B.-1 C. 2 D.3 海海景;把这些卡片的背面朝上搅匀,从中随机抽出一张卡片,抽中正面是桂林山水卡片的概率是( ). A D A. 1 4 B. 7 20 C. 2 5 D. 5 8 10.如图,□ABCD中,AC、BD为对角线,BC=6, B 第 3 题图 C
BC边上的高为 4,则阴影部分的面积为( ). A.3 B.6 C.12 D.24 11.如图所示,在方格纸上建立的平面直角坐标系中, 将△ABO绕点 O按顺时针方向旋转 90°, △ 得 A B O ,则点 A 的坐标为( ). A y B 4 3 2 1 A.(3,1) B.(3,2) -3 -2 -1 0 1 2 3 C.(2,3) D.(1,3) 第 11 题图 12.如图,正方形 ABCD的边长为 2,将长为 2 的线段 QR的两端放 在正方形的相邻的两边上同时滑动.如果 Q点从 A点出发,沿 图中所示方向按 A→B→C→D→A滑动到 A止,同时点 R从 B点 出发,沿图中所示方向按 B→C→D→A→B滑动到 B止,在这个 过程中,线段 QR的中点 M所经过的路线围成的图形的面积为 ( ). A.2 B. 4 π C. π D. π 1 A Q B x M R 第 12 题图 D C 二.填空题(共 6 道小题,每小题 3 分,共 18 分,请将答案填在答题卷上) 13.因式分解: 2 3 x x  . 14.据统计,去年我国粮食产量达 10570 亿斤,用科学记数法表示为 亿斤. 15.如图,在一次数学课外活动中,测得电线杆底部 B与钢缆固定 A 点 C的距离为 4 米,钢缆与地面的夹角为 60º,则这条钢缆在电 线杆上的固定点 A到地面的距离 AB是 米.(结果保留根号). 16.在函数 y  2 x 1  中,自变量 x 的取值范围是 . B 第 15 题图 C y 2 O -1 第 17 题图 x A B C 第 18 题图 A2 A1 D 17.如图,是一个正比例函数的图像,把该图像 向左平移一个单位长度,得到的函数图像的 解析式为 . 18.如图,在△ABC中,∠A=.∠ABC与∠ACD的 平分线交于点 A1,得∠A1;∠A1BC与∠A1CD的平分线相 交于点 A2,得∠A2; ……;∠A2008BC与∠A2008CD的平 分线相交于点 A2009,得∠A2009 .则∠A2009= . 三、解答题(本大题共 8 题,共 66 分,请将答案写在答题卷上.) 19.(本题满分 6 分)计算: 1( 2 ) 1   (2009  0 3)  4sin 30 º- 2
20.(本题满分 6 分)先化简,再求值: 其中 x  2 , y 3 . 1 2 x  1 ( y  x 2 x  2 y  y ) x  2 x , 21.(本题满分 8 分)如图:在等腰梯形 ABCD中,AD∥BC,对角线 AC、BD相交于 O. (1)图中共有 (2)写出你认为全等的一对三角形,并证明. 对全等三角形; A D O B 第 21 题图 C 22. (本题满分 8 分)2008 年 11 月 28 日,为扩大内需,国务院决定在全国实施“家电下乡”政策.第一 批列入家电下乡的产品为彩电、冰箱、洗衣机和手机四种产品.某县一家家电商场,今年一季度对以上 四种产品的销售情况进行了统计,绘制了如下的统计图,请你根据图中信息解答下列问题: 数量(台) 200 150 100 50 手机 40% 洗衣机 冰箱 20% 彩电 彩电 冰箱 洗衣机 手机 品种 (1)该商场一季度彩电销售的数量是 (2) 请补全条形统计图和扇形统计图. 台. 23. (本题满分 8 分)在保护地球爱护家园活动中,校团委把一批树苗分给初三(1)班同学去栽种.如 果每人分 2 棵,还剩 42 棵;如果前面每人分 3 棵,那么最后一人得到的树苗少于 5 棵(但至少分得一 棵). (1)设初三(1)班有 x 名同学,则这批树苗有多少棵?(用含 x 的代数式表示). (2) 初三(1)班至少有多少名同学?最多有多少名 24. (本题满分 8 分)在我市某一城市美化工程招标时,有甲、乙两个工程队投标.经测算:甲队单 独完成这项工程需要 60 天;若由甲队先做 20 天,剩下的工程由甲、乙合做 24 天可完成. (1)乙队单独完成这项工程需要多少天?
(2)甲队施工一天,需付工程款 3.5 万元,乙队施工一天需付工程款 2 万元.若该工程计划在 70 天内 完成,在不超过计划天数的前提下,是由甲队或乙队单独完成该工程省钱?还是由甲乙两队全程合 作完成该工程省钱? 25. (本题满分 10 分)如图,△ABC内接于半圆,AB是直径,过 A作直线 MN, 若∠MAC=∠ABC . (1)求证:MN是半圆的切线; (2)设 D是弧 AC的中点,连结 BD交 AC 于 G, 过 D作 DE⊥AB于 E,交 AC于 F. 求证:FD=FG. (3)若△DFG的面积为 4.5,且 DG=3,GC=4, 试求△BCG的面积. M D C G A N F E 第 25 题图 B 26.(本题满分 12 分)如图,已知直线 分别为 A、B两点. : l y 3 x 4  ,它与 x 轴、 y 轴的交点 3 (1)求点 A、点 B的坐标; (2)设 F是 x 轴上一动点,用尺规作图作出⊙P,使⊙P经过点 B且与 x 轴相切于点 F(不写作法和证明, 保留作图痕迹); (3)设(2)中所作的⊙P的圆心坐标为 P( x (4)是否存在这样的⊙P,既与 x 轴相切又与直线l 相切于点 B,若存在,求出圆心 P的坐标;若不存在, y, ),求 y 与 x 的函数关系式; 请说明理由. y B V A O · F x 2009 年桂林市、百色市初中毕业升学考试 第 26 题图 数学参考答案及评分标准 一、选择题: 题号 1 答案 B 2 A 3 C 4 C 5 B 6 A 7 D 8 B 9 C 10 C 11 D 12 B
二、填空题: 13. ( x x  3) 14.1.057×104 17. y   2 x  或 2 y   2( x  1) 16. x ≥ 1 2 15. 4 3  20092 18. 三、解答题: 19.解:原式=2-1+4× 1 2 20.解:原式  1 2 x  y   ( )  x  1 2 x (    x x -2··············································································· 4 分 =1································································································ 6 分 ( x  )( y x  y )  y 1  x  y y x  2 x ·········································2 分 ·················································································· 3 分 1  x 1 2 x y ) ····························································································· 4 分   ··································································································· 5 分 y 把 x  2 , 代入上式,得原式=3 3 y 2 ·················································· 6 分 21.解:(1)3 …………………………………………………………………………………3 分 (写 1 对、2 对均不给分) (2)△ABC≌△DCB··············································································· 4 分 证明:∵四边形 ABCD是等腰梯形 ∴AB=DC,∠ABC=∠DCB····························································· 6 分 又 BC=CB ∴△ABC≌△DCB ······································································ 8 分 (注:选其它两对证明的,按以上相应步骤给分,全等三角形对应点不对应不扣分) 22.解(1)150 ······················································································· (2 分) (2)10%·························································································· (2 分) (3)每正确补全一个图形给 2 分,其中扇形统计图每补全一个扇形给 1 分. 数量(台) 200 150 100 50 手机 10% 40% 洗衣机 冰箱 20% 彩电 30% 彩电 23.解(1)这批树苗有( 2 x  )棵································································1 分 2 x   2 x  ··················································· 5 分 1) 5   1 1)  ≥ 42 冰箱 42 3( 42 3(   (2)根据题意,得 手机 品种 洗衣机   x x (每列对一个不等式给 2 分) 解这个不等式组,得 40< x ≤44································································· 7 分 答:初三(1)班至少有 41 名同学,最多有 44 名同学.········································· 8 分
24.解:(1)设乙队单独完成需 x 天··································································· 1 分  ············································ 3 分 根据题意,得 ) 24 1  20 (    1 60 1 x 1 60 解这个方程,得 x =90······································································ 4 分 经检验, x =90 是原方程的解 ∴乙队单独完成需 90 天··································································· 5 分 (2)设甲、乙合作完成需 y 天,则有 ( 1 60  1 90 ) y  1 解得 36 y  (天)··················································································6 分 甲单独完成需付工程款为 60×3.5=210(万元) 乙单独完成超过计划天数不符题意(若不写此行不扣分). 甲、乙合作完成需付工程款为 36(3.5+2)=198(万元)······························· 7 分 答:在不超过计划天数的前提下,由甲、乙合作完成最省钱.······················· 8 分 25.证明(1):∵AB是直径 ∴∠ACB=90º ,∴∠CAB+∠ABC=90º················································· 1 分 ∵∠MAC=∠ABC ∴∠MAC+∠CAB=90º,即 MA⊥AB ∴MN 是半圆的切线.······························ 2 分 M (2)证法 1: ∵D是弧 AC的中点, ∴∠DBC=∠2············ 3 分 ∵AB是直径,∴∠CBG+∠CGB=90º ∵DE⊥AB,∴∠FDG+∠2=90º··················· 4 分 ∵∠DBC=∠2,∴∠FDG=∠CGB=∠FGD ∴FD=FG················································ 5 分 证法 2:连结 AD,则∠1=∠2························· 3 分 D H 3 1 F E A N ∵AB是直径,∴∠ADB=90º ∴∠1+∠DGF=90º C G 2 B 又∵DE⊥AB ∴∠2+∠FDG=90º·························································· 4 分 ∴∠FDG=∠FGD, ∴FD=FG····························································· 5 分 (3)解法 1:过点 F作 FH⊥DG于 H,························································ 6 分 1 2 1 2 9 4 又∵DF=FG ∴S△FGH= S△DFG= ×4.5= ··········································· 7 分 ∵AB是直径,FH⊥DG ∴∠C=∠FHG=90º·········································· 8 分 ∵∠HGF=∠CGB,∴△FGH∽△BGC ∴ S  S  FGH  ( BGC HG CG 2 )  ( 1.5 4 2 )  9 64 ·····················································9 分 ∴S△BCG= 9 64 16  4 9  ······································································10 分 解法 2:∵∠ADB=90º,DE⊥AB,∴∠3=∠2················································ 6 分 ∵∠1=∠2, ∴∠1=∠3
∴AF=DF=FG·············································································· 7 分 ∴S△ADG=2S△DFG=9··········································································· 8 分 ∵∠ADG=∠BCG,∠DGA=∠CGB ∴△ADG∽△BCG········································································ 9 分 ) 2  ( 24 ) 3  16 9 ∴ S S △ BCG △ ADG (  CG DG 16 9 16 9   ∴S△BCG= ····································································· 10 分 解法 3:连结 AD,过点 F作 FH⊥DG于 H, ∵S△FDG= DG×FH= ×3FH=4.5 1 2 1 2 ∴FH=3······················································································· 6 分 ∵H是 DG的中点,FH∥AD ∴AD=2FH=6 ················································································· 7 分 ∴S△ADG= 1 2 AD DG 1 6 3 9     ···················································· 8 分 2 (以下与解法 2 同) 26.解(1)A( 4 ,0),B(0,3)········································2 分(每对一个给 1 分) (2)满分 3 分.其中过 F作出垂线 1 分,作出 BF中垂线 1 分,找出圆心并画出⊙P给 1 分. (注:画垂线 PF不用尺规作图的不扣分) (3)过点 P作 PD⊥ y 轴于 D,则 PD= x ,BD= 3 y ,··············6 分 PB=PF= y ,∵△BDP为直角三形, ∴ 2 PB  2 PD BD  2 ∴ 2 BP  2 PD BD  2 ························· 7 分 y B D O P F x 即 2 y  2 x 3   y 2 即 2 y  2 x  (3  2 y ) ∴ y 与 x 的函数关系为 y 21 x 6 A  ································································ 8 分 3 2 (4)存在 解法 1:∵⊙P与 x 轴相切于点 F,且与直线l 相切于点 B ∴ AB AF ································································································· 9 分 ∵ 2 AB OA OB   2 2  25 ∴ 2 AF  25 ∵AF= 4x  , ∴ ( x  4) 2  2 5 ···································································10 分 ∴ 1  x  或 x 9 ·························································································· 11 分
把 1  x  或 x 9 代入 ∴点 P的坐标为(1, 21 x 6  ,得 3 2 y  5 3 或 y 15 )或(  9,15)·························································· 12 分 y 5 3
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