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2009年湖南省湘西自治州中考数学真题及答案.doc

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2009 年湖南省湘西自治州中考数学真题及答案 姓名: -------------------------------------------------------------------------------------------- --------------------- 注意事项: 准考证号: 1、本卷为试题卷,考生应在答题卡上作答,在试题卷、草稿纸上答题无效. 2、答题前,考生须先将自己的姓名、准考证号分别在试题卷和答题卡上填写清楚. 3、答题完成后,请将试题卷、答题卡、草稿纸放在桌上,由监考老师统一收回. 4、本试卷三大题,25 小题,时量 120 分钟,满分 120 分. -------------------------------------------------------------------------------------------- --------------------- 一、填空题(本大题 8 小题,每小题 3 分,共 24 分. 将正确答案填在答题卡相应横线上) 1.数 3 的绝对值是 . 2.用代数式表示“a与 b的和”,式子为 . 3.如果 x-y<0,那么 x与 y的大小关系是 x y .(填<或>符号) 4.一个圆的半径是 4,则圆的面积是 .(答案保留π) 5.一次函数 3  y x b  的图像过坐标原点,则 b的值为 . 6.长方形一条边长为 3cm,面积为 12cm2,则该长方形另一条边长为 cm. 7.截止到 2008 年底,湘西州在校小学生中的少数民族学生数约为 21.2 万人,约占全州小学生总数的 80%, 则全州的小学生总数大致为 万.(保留小数点后一位) 8.对于任意不相等的两个数 a,b,定义一种运算※如下:a※b= ba  ba  , 如 3※2= 23  23   5 .那么 12※4= . 二、选择题(本大题 8 个小题,每小题 3 分,共 24 分. 将每个小题所给四个选项中惟一正确选项的代号 在答题卡上填涂) 9. 一个角是 80°,它的余角是( ) A.10° B.100° C.80° D.120° 10.要了解一批电视机的使用寿命,从中任意抽取 40 台电视机进行试验,在这个问题中,40 是( ) A.个体 B.总体 C.样本容量 D.总体的一个样本
11.在下列运算中,计算正确的是( ) A. 3 a a  2  6 a C. 8 a  2 a  4 a B. 2 3 )a ( 5 a D. 2 2 )ab ( 2 4 a b 12.在直角坐标系中,点M(sin50°,-cos70°)所在的象限是( ) A. 第一象限 B. 第二象限 C. 第三象限 D. 第四象限 13.在下列命题中,是真命题的是( ) A.两条对角线相等的四边形是矩形 B.两条对角线互相垂直的四边形是菱形 C.两条对角线互相平分的四边形是平行四边形 D.两条对角线互相垂直且相等的四边形是正方形 14. O⊙ 的半径为 10cm,弦 AB=12cm,则圆心到 AB的距离为( ) A. 2cm B. 6cm C. 8cm D. 10cm 15.一个不透明的袋中装有除颜色外均相同的 3 个红球和 2 个黄球,从中随机摸出一个,摸到黄球的概率 是( A. 2 3 l 16.如图,1 // A.20° C.50° ) B. 1 5 C. 2 5 l ,∠1=120°,∠2=100°,则∠3= ( 2 ) D. 3 5 B.40° D.60° 3 2 1 l1 l2 三、解答题(本大题 9 小题,共 72 分,每个题目都要求在答题卡的相应位置写出计算或证明的主要步骤) 17.(本题 5 分)先化简再计算: 2 2 x x   y y  2 x  y ,其中 x =3, y =2. 18.(本题 5 分)解方程: 2 2 x x        y y 7 5 ① ② 19.(本题 6 分)如图,在△ABC中,DE∥BC, EF∥AB,求证:△ADE∽△EFC. A D B E F C 20.(本题 6 分)吉首某中学九年级学生在社会实践中,向市区的中小学教师调查他们的学历情况,并将
调查结果分别用下图的扇形统计图和折线统计图(不完整)表示. (1) 求这次调查的教师总数; 研究生 中师 专科 本科 其它 学历结构 (2) 补全折线统计图. 21.(本题 6 分)在反比例函数 y  的图像的每一条曲线上, y 都随 x 的增大而减小. k x (1) 求 k 的取值范围; (2) 在曲线上取一点 A,分别向 x 轴、 y 轴作垂线段,垂足分别为 B、C,坐标原 点为 O,若四边形 ABOC面积为 6,求 k 的值. 22.(本题 6 分)如图,在离水面高度为 5 米的岸上有人用绳 岸,开始时绳子与水面的夹角为 30°,此人以每秒 0.5 (1) 未开始收绳子的时候,图中绳子 BC的长度是 多少米? (2) 收绳 8 秒后船向岸边移动了多少米?(结果保留根号) 子 拉 船 靠 米收绳.问: 23.(本题 8 分)2009 年 5 月 22 日,“中国移动杯”中美篮球对抗赛在吉首进行.为组织该活动,中国移 动吉首公司已经在此前花费了费用 120 万元.对抗赛的门票价格分别为 80 元、200 元和 400 元.已知 2000 张 80 元的门票和 1800 张 200 元的门票已经全部卖出.那么,如果要不亏本,400 元的门票最低 要卖出多少张? 24.(本题 10 分)如图,等腰直角△ABC腰长为 a,现分别按图 1、图 2 方式在△ABC内内接一个正方形 ADFE 和正方形 PMNQ.设△ABC的面积为 S,正方形 ADFE的面积为 S1,正方形 PMNQ的面积为 S2,
(1) 在图 1 中,求 AD∶AB的值;在图 2 中,求 AP∶AB的值; (2) 比较 S1+S2 与 S的大小. A D E A P Q B F 图 1 C B M N 图 2 C 25.(本题 20 分)在直角坐标系 xoy中,抛物线 y  2 x  bx  与 x轴交于两点 A、B,与 y轴交于点 C, c 其中 A在 B的左侧,B的坐标是(3,0).将直线 y kx 沿 y轴向上平移 3 个单位长度后恰好经过点 B、 C. (1) 求 k的值; (2) 求直线 BC和抛物线的解析式; (3) 求△ABC的面积; (4) 设抛物线顶点为 D,点 P在抛物线的对称轴上,且∠APD=∠ACB,求点 P的坐标. 2009 年湘西自治州初中毕业学业考试数学参考答案 一、(本题 8 小题,每题 3 分,共 24 分,填错记 0 分) 1.3; 2.a+b; 3.<; 4.16π; 5.0; 6.4; 7.26.5; 8.1/2
二、(本题 8 小题,每题 3 分,共 24 分,选错记 0 分) 9.A 10.C 11.D 12.D 13.C 14.C 15.C 16.B 三、(本题 9 个题,共 72 分) 17.(本题 5 分) )( xy y x  解:原式=  ( x ( y )  )  2 x  y ····································································· 2 分 =x+y-2x+y =-x+2y ······················································································· 4 分 因为 x=3,y=2 所以原式=-3+4=1 ············································································ 5 分 18.(本题 5 分) 解:①+② 得 4x=12,即 x=3 代入① 有 6-y=7,即 y=-1 ··································································2 分 ···························································· 4 分 所以原方程的解是: x y    3   1 ··········································································5 分 19.(本题 6 分) 证明:∵DE∥BC,∴DE∥FC,∴∠AED=∠C ······················································· 3 分 又∵EF∥AB,∴EF∥AD,∴∠A=∠FEC ······················································· 5 分 ∴△ADE∽△EFC ················································································· 6 分 20.(本题 6 分) 解:(1)总人数= 275 55% 500   人 (2)教师中专科学历的人数=500 10% 50  ················································· 3 分  人 ········································· 4 分 作图: ····························································································· 6 分 注:第(2)问虽然没明确指出专科人数 为 50,但只要作图准确就可得 6 分. 研究生 中师 专科 本科 其它 学历结构 21.(本题 6 分) 解(1)因为 y的值随 x的增大而减小,所以 k>0 ············································· 2 分 (2)设 A(x0,y0) ································································ 4 分 则由已知,应有|x0y0|=6 即|k|=6 而 k>0 所以 k=6. ······················································································ 6 分 22.(本题 6 分)
解(1)如图,在 Rt△ABC中, ∴ BC= 5 sin30  =10 米 AC =sin30° ···················································· 2 分 BC ·······················································3 分 (2)收绳 8 秒后,绳子 BC缩短了 4 米,只有 6 米, ······································ 4 分 这时,船到河岸的距离为 2 6  2 5  36  25  11 米.·································· 6 分 23.(本题 8 分) 解:2000 张 80 元的门票收入为 2000×80=160000 元; ······································· 2 分 1800 张 200 元的门票收入为 1800×200=360000 元;······································· 4 分 1200000-160000-360000=680000 元,························································ 5 分 故 400 元的门票至少要卖出:680000÷400=1700 张. 答:400 元的门票最少要卖出 1700 张.························································ 8 分 24.(本题 10 分) 解(1)图 1 中,∵AD=DF,∠B=45°,从而 DF=DB,∴AD=DB, ∴AD∶AB=1∶2 ··································································· 2 分 图 2 中,∵PM=MN,∠B=45°,从而 PM=MB,∴MN=MB, ∴MN=MB=NC, ∴AP∶AB=PQ∶BC=MN∶BC=1∶3 ····························································4 分 (2)图 1 中,S1=    1 2 a 2    1 4 2 a ···································································· 6 分 又 PQ∶BC=AP∶AB=1∶3, ∴PQ= 2 3 a ,∴S2=    2 3 a 2    2 9 2 a ································································· 8 分 从而 S1+S2= 1    4  2 9    2 a  17 36 2 a 又 S= 1 2 2 a  18 36 2 a ∴S1+S2<S·····································································································10 分 25.(本题 20 分) 解(1)直线 y kx 沿 y轴向上平移 3 个单位后,过两点 B,C 从而可设直线 BC的方程为 y kx  ···································································2 分 3 x  ,得 C(0,3)···················································································· 3 分 k   ······································································································· 5 分 x   ·························································7 分 (2)由(1),直线 BC 的方程为 3 y 令 0 又 B(3,0)在直线上, ∴ 0 3 ∴ 3k  1 又抛物线 y  2 x  bx  过点 B,C c
∴ 3 c    39 cb    0  b   c  4  3  ∴抛物线方程为 y  x 2 4  x  ········································································ 10 分 3 (3)由(2),令 2 4 x x   3 0 x 得 1  1 , x 2 3 ···························································································· 12 分 即 A(1,0),B(3,0),而 C(0,3) ∴△ABC的面积 S△ABC= (3-1)·3=3 平方单位····················································15 分 1 2 (4)由(2),D(2, 1 ),设对称轴与 x轴交于点 F,与 BC交于 E,可得 E(2,1), 连结 AE.  ∵ AF FB FE   1 ∴AE⊥CE,且 AE= 2 ,CE= 22 (或先作垂线 AE⊥BC,再计算也可) 在 Rt△AFP与 Rt△AEC中, ∵∠ACE=∠APE(已知) 1 = 2 PF 22 即 ∴ PF CE 2 AF  AE PF  ·····························································18 分 ∴ ∴点 P的坐标为(2,2)或(2, 2 )······················· 20 分 (x轴上、下方各一个) (注:只有一个点扣 1 分)
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