广东省九年级数学中考模拟试卷
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重点中学——星华学校初三数学模拟试卷说明:全卷共4页,考试时间为100分钟,满分120分.请在答题卡上作答.(出卷者:倪迁华)一、选择题(本大题10小题,每小题3分,共30分)在每小题列出的四个选项中,只有一个是正确的,请把答题卡上对应题目所选的选项涂黑. 1.有理数的绝对值为( )A .B .C .D .2.我们虽然把地球称为“水球”,但可利用淡水资源匮乏.我国淡水总量仅约为899000亿米3,用科学记数法表示这个数为( ) A .0.899×104亿米3B .8.99×105亿米3C .8.99×104亿米3D .89.9×104亿米33.下列图形中对称轴只有两条的是( )A .圆B .等边三角形C .矩形D .等腰梯形 4.计算:=( )A .3B .C .D .4 5.已知等腰三角形的一个底角等于30°,则这个等腰三角形的顶角等于( ) A 、150° B 、120° C 、75° D 、30° 6.如图所示的几何体的正视图是( )7.如图,直线AB ∥CD ,∠A =70︒,∠C =40︒,则∠E 等于( )A .30° B.40° C .60° D.70°8.袋子内有3个红球和2个蓝球,它们只有颜色上的区别,从袋子中随机地取出一个球,取出红球的概率是( ) A . B .C .D .9.计算的结果是( ) A .B .C .D .10.如图,在等腰梯形ABCD 中,BC ∥AD ,AD =5,DC =4,DE ∥AB 交BC 于点E ,且EC =3,则梯形ABCD 的周长是( )ACBD E第7题图第10题图A .21B .25C .26D .20二、填空题(本大题6小题,每小题4分,共24分)请将下列各题的正确答案填写在答题卡相应的位置上. 11.分解因式:=___ ___.12.已知正比例函数,点(2,﹣3)在函数上,则随的增大而 (增大或减小). 13.如图,AB 为⊙O 的直径,CD 为⊙O 的一条弦, CD ⊥AB ,垂足为E ,已知CD =6,AE =1, 则⊙O 的半径为 .14.在学校艺术节文艺汇演中,甲、乙两个舞蹈队队员的身高的方差分别是S甲2=1.5,S乙2=2.5,那么身高更整齐的是 队(填“甲”或“乙”). 15.不等式组:的解集是 .16.观察下列图形的排列规律(其中、、分别表示三角形、正方形、五角星),若第一个图形是三角形,则第18个图形是 .(填图形名称)三、解答题(一)(本大题3小题,每小题6分,共18分) 17.计算:18先化简,再求值:a -1a +2·a2+2a a2-2a +1÷1a2-1,其中a 为整数且-3<a <2.19.如图,Rt △ABC 的斜边BC =8,AC =6(1)用尺规作图作AB 的垂直平分线,垂足为D ,(保留作图痕迹,不要求写作法、证明);(2)连结D 、C 两点,求CD 的长度.四、解答题(二)(本大题3小题,每小题8分,共24分) 20.如图,某同学在楼房的A 处测得荷塘的一端B 处的俯角为,荷塘另一端D 处与C 、B 在同一条直线上,已知AC=32米,CD=16米,求荷塘宽BD 为多少米?(取,结果保留整数)第13题图C BA第19题图21.已知一元二次方程的一根为 2.(1)求关于的关系式;(2)若,求方程的另一根;(3)求证:抛物线与轴有两个交点.22.某中学为了解本校学生对球类运动的爱好情况,采用抽样的方法,从乒乓球、羽毛球、篮球和排球四个方面调查了若干名学生,在还没有绘制成功的“折线统计图”与“扇形统计图”中,请你根据已提供的部分信息解答下列问题。
(1)在这次调查活动中,一共调查了名学生,并请补全统计图;(2)“羽毛球”所在的扇形的圆心角是度;(3)若该校有学生1200名,估计爱好乒乓球运动的约有多少名学生?五、解答题(三)(本大题3小题,每小题9分,共27分)23.如图,在平面直角坐标系中,函数的图象与一次函数的图象交点为A(m,2).(1)求一次函数的解析式;(2)设一次函数的图象与轴交于点B,若P是轴上一点,且满足△PAB的面积是4,直接写出P的坐标.24.如图1,在△ABC 和△EDC 中,AC =CE =CB =CD ,∠ACB =∠ECD =,AB 与CE 交于F ,ED与AB 、BC 分别交于M 、H .(1)求证:CF =CH ;(2)如图2,△ABC 不动,将△EDC 绕点C 旋转到∠BCE =时,试判断四边形ACDM 是什么四边形?并证明你的结论.25. 已知,如图,在平面直角坐标系中,Rt △ABC 的斜边BC 在轴上,直角顶点A 在轴的正半轴上,A (0,2),B (-1,0)。
(1)求点C 的坐标;(2)求过A 、B 、C 三点的抛物线的解析式和对称轴;(3)设点P (m ,n )是抛物线在第一象限部分上的点,△PAC 的面积为S ,求S 关于m 的函数关系式,并求使S 最大时点P 的坐标.A(图1) (图2)(24题图)九年级数学第一次模拟题参考答案和评分标准一、ABCBB DACDA二、11、 12、减小 13、5, 14、甲15、16、五角星.三、解答题(一)(本大题3小题,每小题5分,共15分)17.解:原式= ···································································· 4分=··························································································· 5分18.解:设原计划平均每亩产量是万斤根据题意得:······························································· 2分解得: ····················································································· 4分经检验:是原方程的根答:改良前亩产0.3万斤,改良后亩产0.45万斤. ······································· 5分19.解:(1)作图正确(不保留痕痕迹的得1分), ··········································· 3分(2)因为在中,BC=8,AC=6∴, ························································· 4分∴········································································ 5分四、解答题(二)(本大题3小题,每小题8分,共24分)20.解:如图,依题意得:∠BAC =60°, ·························································· 2分在Rt△ABC中,∵∠BAC=, ····················································· 3分∴BC=60° ····································································· 6分∴荷塘宽(米) ····································· 7分答:约荷塘宽BD约为39米 ··································································· 8分21.解:(1)∵A(m,2)在函数的图象上∴,········································································ 2分∴A(2,2)∵A(2,2)一次函数的图象上∴, ···································································· 3分∴一次函数的解析式为:························································· 4分(2),·········································································· 8分22.解:(1)200 ························································································· 2分∵喜欢篮球的人数:200×20%=40(人)喜欢羽毛球的人数:200-80-20-40=60(人)喜欢排球的20人,应占℅=10℅喜欢羽毛球的应占统计图的1-20%-40%-10%=30%∴根据以上数据补全统计图:·································································· 4分(2)108°···························································································· 6分(3)该校1200名学生中估计爱好乒乓球运动的约有:40%×1200=480(人) ····································································· 8分五、解答题(三)(本大题3小题,每小题9分,共27分)23.解:(1)代入方程得:·············································································· 1分························································································ 2分(2)若,则,∴········································· 3分原方程变为: ······································································ 4分∴,方程的另一根为0 ·················································································· 5分(3)∵······························ 6分········································································· 7分∴方程有两个不等的实根·················································· 8分∴抛物线与轴有两个交点.············································ 9分24.解:(1)证明:在△ACB和△ECD中∵∠ACB=∠ECD=∴∠1+∠ECB=∠2+∠ECB,∴∠1=∠2········································································ 1分又∵AC=CE=CB=CD,∴∠A=∠D=····································································· 2分∴△ACF≌△DCH, ···························································· 3分∴CF=CH ············································································· 4分(2)答: 四边形ACDM是菱形 ······························································· 5分证明: ∵∠ACB=∠ECD=, ∠BCE=∴∠1=, ∠2= ···················································· 6分又∵∠E=∠B=,∴∠1=∠E, ∠2=∠B······················································· 7分∴AC∥MD, CD∥AM ,∴ACDM是平行四边形 ···················································· 8分又∵AC=CD, ∴ACDM是菱形········································ 9分25.解:(1)∵A(0,2),B(-1,0),∴OA=2,OB=1。