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2009年广西崇左市中考数学真题及答案.doc

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2009 年广西崇左市中考数学真题及答案 (全卷满分:120 分;考试时间:120 分钟) 一、填空题:本大题共 10 小题;每小题 2 分,共 20 分.请将答案填写在题中的横线上. 1. 5 的绝对值是 75 2.已知 A  °,则 A 的余角的度数是 . . 3.在函数 y x  中,自变量 x 的取值范围是 3 . 4.分解因式: 22 x 4 x   2 . 5.写出一个图像位于第一、二、三象限内的一次函数表达式: 6.一元二次方程 2 x mx   的一个根为 1 ,则另一个根为 3 0 . . 的母线长为 O C A (第 8 题) B D A (第 10 题) c 1 P 2 5 3 4 (第 11 题) C E B a P b P 半径的半圆 为 的四个选项 小题选对得 ( ) 7.已知圆锥的侧面积为 8πcm ,侧面展开图的圆心角为 45°,则该圆锥 2 cm. 8.如图,点O 是 O⊙ 的圆心,点 A B C、 、 在 O⊙ 上, AO BC∥ , AOB 的度数是 38 . 9.当 x ≤ 0 时,化简 10.如图,正方形 ABCD 中,E 是 BC 边上一点,以 E 为圆心、EC 为 与以 A 为圆心, AB 为半径的圆弧外切,则sin EAB 的结果是 的值 . x 2  °,则 OAC 1 x   . 二、选择题:本大题共 8 小题;每小题 3 分,共 24 分.在每小题给出 中,只有一项是正确的,请将正确答案前的字母填入题后的括号内,每 3 分,选错、不选或多选均得 0 分. 11.如图,直线 c 截二平行直线 a b、 ,则下列式子中一定成立的是 A. 1 C. 1 12.下列运算正确的是( 3    5    )       B. 1 D. 1 2 4 A. 2 x 2 3 6 x· x 2 4 B. 2 x 2 2 3 x 1   C. 2 x 2 2  3 x  22 x 3 D. 2 x 2  2 3 x  4 5 x 13.一个等腰三角形的两边长分别为 2 和 5,则它的周长为( A.7 D.9 或 12 B.9 ) 14.不等式组 的整数解共有( ) C.12 2  ≤    2 1 x  x B.4 个 A.3 个 \ 15.如图,下列选项中不是..正六棱柱三视图的是( C.5 个 D.6 个 )
A. B. C. D. 16.某校九年级学生参加体育测试,一组 10 人的引体向上成绩如下表: 完成引体向上的个数 人 数 7 1 8 1 9 3 10 5 )   °, E A B 1 F (第 17 题) D C 则 AEF = 绕点O 按逆 B.9.5 和 10 这组同学引体向上个数的众数与中位数依次是( A.9 和 10 C.10 和 9 D.10 和 9.5 17.如图,把矩形 ABCD 沿 EF 对折后使两部分重合,若 1 50 ( A.110° D.130° B.115° C.120° ) 18.已知点 A 的坐标为 ( a b, ,O 为坐标原点,连结OA ,将线段OA ) 时针方向旋转 90°得 1OA ,则点 1A 的坐标为( ) A.( a b  , ) B. ( a b, ) C. ( b a  , ) D. ( b a, ) 三、解答题:本大题共 7 小题,共 76 分. 19.(本小题满分 6 分) 计算: 2sin 60  ° 3tan 30  ° 0    1 3      ( 1) 2009 . 20.(本小题满分 8 分) 已知 2 2 0 x   ,求代数式 ( x x 2 1)  2 1   2 x x  1 的值. 21.(本小题满分 10 分)
如图, ABC△ 中, D E、 分别是边 BC AB、 的中点, AD CE、 相交于G .求证: A GE GD AD CE   . 1 3 E G B D (第 21 题) C 22.(本小题满分 10 分) 一只口袋中放着若干只红球和白球,这两种球除了颜色以外没有任何其他区别,袋中的球已经搅匀,蒙上 眼睛从口袋中取出一只球,取出红球的概率是 1 4 . (1)取出白球的概率是多少? (2)如果袋中的白球有 18 只,那么袋中的红球有多少只? 23.(本小题满分 12 分) 五一期间某校组织七、八年级的同学到某景点郊游,该景点的门票全票票价为 15 元/人,若为 50~99 人可 以八折购票,100 人以上则可六折购票.已知参加郊游的七年级同学少于 50 人,八年级同学多于 50 人而少 于 100 人.若七、八年级分别购票,两个年级共计应付门票费 1575 元,若合在一起购买折扣票,总计应付 门票费 1080 元.问: (1)参加郊游的七、八年级同学的总人数是否超过 100 人? (2)参加郊游的七、八年级同学各为多少人? 24.(本小题满分 14 分) 如图,在等腰梯形 ABCD 中,已知 AD BC∥ ,  AB DC AD ,  2 , BC  4 ,延长 BC 到 E ,使CE AD .
(1)证明: BAD (2)如果 AC BD △ DCE ≌△ ,求等腰梯形 ABCD 的高 DF 的值. ; A D B CF (第 24 题) E 25.(本小题满分 16 分) 在平面直角坐标系中,现将一块等腰直角三角板 ABC 放在第二象限,斜靠在两坐标轴上,且点 (0 2) A , ,  ax  经过点 B . C  , ,如图所示:抛物线 点 ( 1 0) (1)求点 B 的坐标; (2)求抛物线的解析式; (3)在抛物线上是否还存在点 P (点 B 除外),使 ACP△ 存在,求所有点 P 的坐标;若不存在,请说明理由. 2 y 2 ax  仍然是以 AC 为直角边的等腰直角三角形?若 y A (0,2) B (-1,0) C x 2009 年崇左市初中毕业升学考试 数 学 答 案 一、1.5 2.15° 3. x ≥ 3 4. 2( x  1) 2 6. 3 7.8 8.19° 9.1 10. 3 5 (第 25 题) y x  等 1 5. 二、11.B 12.A 13.C 14.C 15A 16.D 17.B 18.C 三、19.原式= 2  3 2 3   3 3 1 1   ··································································4 分 =0.····························································································6 分 20.原式= 1) ( x  1)( x  ( x 2  1)  2 x x  1 ·········································································· 2 分 = x x   1 1  2 x x  1 ····················································································4 分
2 x = 1 x   1 x  ·······················································································5 分  2 2 0 x   , 2 x  ··························································································6 分 原式  1 ··············································································· 7 分 2 2   1 x x  原式=1··························································································· 8 分 A G E B D C   AC ∽△ △ ∥ , ACG  D E DE ,··············································· 3 分 21.证明:连结 ED ,·················································· 1 分  、 分别是边 BC AB、 的中点,  1 DE 2 AC DEG ,················································· 5 分 1 GE GD DE 2 GC AG AC GE GD CE AD P 22.(1) ( 3 4  ,············································ 7 分 1 P   ( 1 4 1 3 取出白球    = ) )  .························································································10 分 取出红球 ········································································ 3 分 x   18 3 4 (或 18  x 18  x    ····································································································· 4 分 1 (2)设袋中的红球有 x 只,则有········································································ 5 分 )······································································ 8 分 1 4 x 解得 6 所以,袋中的红球有 6 只.·············································································· 10 分 23.(1)全票为 15 元,则八折票价为 12 分,六折票价为 9 元.·······························2 分 ················································································· 4 分  参加郊游的七、八年级同学的总人数必定超过 100 人.········································5 分 (2)设七、八年级参加郊游的同学分别有 x 人、 y 人············································ 6 分 由(1)及已知, 50 50 , .············································ 7 分 100 15 1500 1575     100 100 x ,     y x y 依题意可得: 15 x   9( x  12 1575 y ) 1080 y     ························································································ 10 分 解得 45 75 ·······································································································11 分 x    y 答:参加郊游的七、八年级同学分别为 45 人和 75 人.········································· 12 分 24.(1)证明: AD BC .··············································· 1 分  ∥ , CDA DCE   
   ,   ,    CDA ≌△  △ 是等腰直角三角形,即 , DE BD 45 E  °, DCE DF FE FC CE  .·············································································· 12 分 BAD  BAD  AB DC AD CE   , ≌△  AC DE AC BD DE BD ,·········································· 2 分 DCE .······················································································ 3 分  DCE 又四边形 ABCD 是等腰梯形, BAD   △ .·····················································································5 分 (2) AD CE AD BC , ∥ , 四边形 ACED 是平行四边形,······························ 7 分  ∥ .······························································································· 8 分  .··············································································9 分  由(1)可知, BAD .··············································10 分 所以, BDE△   四边形 ABCD 是等腰梯形,而 FC  .·································································································· 13 分  DF 25.(1)过点 B 作 BD x 轴,垂足为 D , CAO BCD   BCD     又 BCD △ ,········································· 2 分   ····························· 3 分 点 B 的坐标为 ( 31) , ;······································ 4 分  .································································································· 14 分  ;···········································1 分     ACO CAO COA   CAO ≌△ 1  , N O M P1 CE AD BD OC CD OA  CB AC  2 , BC ACO BDC   AD 90 90 90 °,   2  2 °; 4 , 1 3 B D y A  ° , C  P2 x (2)抛物线 y  2 ax  ax B  , ,则得到1 9  a  3 a  ,·····················5 分 2 解得 a  ,所以抛物线的解析式为  x  ;········································7 分 2 1 2 2  经过点 ( 31) 21 x 2  y 1 2 (3)假设存在点 P ,使得 ACP△ ① 若以点C 为直角顶点; 仍然是以 AC 为直角边的等腰直角三角形: 则延长 BC 至点 1P ,使得 1PC BC ,得到等腰直角三角形 1ACP△ ,······················· 8 分 过点 1P 作 1PM x 轴,  CP BC  1 ,  MCP 1   BCD ,  PMC 1   BDC  90 °; △ 1MPC ≌△ DBC ······················································································10 分  CM CD   2 , PM BD 1   1 ,可求得点 1P(1,-1);···································· 11 分 ② 若以点 A 为直角顶点; 则过点 A 作 2AP CA ,且使得 2AP AC ,得到等腰直角三角形 2ACP△ ,············ 12 分 过点 2P 作 2P N y 轴,同理可证 △ 2AP N ≌△ CAO ;·········································13 分
 NP OA  2  2 , AN OC   1 P , ;·········································· 14 分 经检验,点 1(1 1) P , 与点 2(2 1) P , 都在抛物线 y ,可求得点 2(2 1) 21 x 2   1 2 x  上.························ 16 分 2
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