发布时间 : 星期五 文章内蒙古鄂尔多斯市中考真题更新完毕开始阅读
24．（本小题满分9分） 在“5·12大地震”抗震救灾期间，甲、乙两个帐篷生产厂不断提高帐篷生产量．帐篷总产量y（顶）随时间t（天）之间的变化成直线（折线段）上升趋势，如图所示．请你结合图象填空和解答问题： （1）甲、乙两厂生产帐篷的总产量y与时间t之间的函数解析式为： ?20t(0≤t≤3)? y甲??；y乙?? 50t?90(3?t≤5) ??（2）截止5月17日，甲、乙两厂合计共生产帐篷 顶；帐篷总产量最先达到120顶的是 厂（填甲或乙）；5月15日这一天，甲厂生产了 顶帐篷． ．．．（3）乙厂在5月18日又一次提高了生产效率，这样乙厂每天只比甲厂少生产5顶帐篷，求乙厂每天生产帐篷的数量提高了百分之几？ y(顶) 甲（粗实线） 160 140 乙（细实线） 130 120 100 80 60 40 20 10 0 1 2 3 4 5 t(天) 5月13日 5月14日 5月15日 5月16日 5月17日 第24题图 25．（本小题满分9分） 已知，如图，在Rt△ABC中，?ABC?90，点D是AC的中点，?O经过B，C，D?三点，与AB交于另一点E． （1）请你仔细观察图形，连接图中已标明字母的某两点，得到一条新线段，证明它与线段AE相等． （2）在图中，过点E作?O的切线，交AD于点F． ①求证：EF?FD?FC； ②若AF?DF，求sinA的值． D A O 2C E B 第25题图 26．（本小题满分12分） 如图，点D，E分别是矩形OABC中AB和BC边上的中点，点B的坐标为（6，4）． （1）写出A，D，E，C四点的坐标；并判断点O到直线DE的距离是否等于线段OE的长． （2）动点F在线段DE上，FG?x轴于G，FH?y轴于H，求矩形OGFH面积最大时F点的坐标．（利用图1解答） （3）我们给出如下定义：分别过抛物线上的两点（不在x轴上）作x轴的垂线，如果以这两点及垂足为顶点的矩形在这条抛物线与x轴围成封闭图形内部，则称这个矩形是这条抛物线的内接矩形．请你理解上述定义，解答下面的问题：若矩形OABC是某个抛物线的周长最大的内接矩形，求这个抛物线的解析式．（利用图2解答） y y y E E E B B B C C C F H D D D O O O G A A A x x x 第26题图 图1 图2 2008年鄂尔多斯市初中毕业升学考试卷 数学试题参考答案及评分说明 （一）阅卷评分说明 1．正式阅卷前先进行试评，在试评中认真阅读参考答案，明确评分标准，不得随意拨高或降低评分标准．试评的试卷必须在阅卷后期予以复查，防止阅读前后期评分标准宽严不一致． 2．评分方式为分步累计评分，解答过程的某一步骤发生笔误，只要不降低后继部分的难度，而后继部分再无新的错误，后继部分可评应得分数的50%；若是几个相对独立的得分点，其中一处错误不影响其它得分点的评分． 3．最小记分单位为1分，不得将评分标准细化至1分以下（即不得记小数分）． 4．解答题题头一律记该题的实际得分，不得用记负分的方式记分．对解题中的错误须用红笔标出，并继续评分，直至将解题过程评阅完毕，并在最后得分点处标上该题实际得分． 5．本参考答案只给出一至两种解法，凡有其它正确解法都应参照本评分说明分步确定得分点，并同样实行分步累计评分． 6．合理精简解题步骤者，其简化的解题过程不影响评分． （二）参考答案及评分标准 一、选择题（本大题10个小题，每小题3分，共30分） 题号 选项 1 B 2 C 3 D 4 D 5 C 6 C 7 B 8 B 9 A 10 D 二、填空题（本大题8个小题，每小题3分，共24分） 11．?1 12．?1（只要填一个负数即可） 13．有一个角是直角或对角线相等或邻边垂直 14．k?0或k等于一个正数，如k?1 15．图中的阴影正方形 16．25 17．62 18．5 第15题图 三、解答题（本大题8个小题，共66分） 19．（本小题满分8分） （1）解方程x32?2?1 x?4x?16解：x32······························································································· 1分 ??1 x?4(x?4)(x?4)······························································································ 2分 x(x?4)?32?(x?4)(x?4) ································································································································ 3分 ?x?4． ·经检验：x?4是增根，原方程无解 ····················································································· 4分 ?2(2?x)≤4 ①?（2）解不等式组?x?1，并将解集表示在数轴上． ?1 ②??2解：解不等式①得x≥0 ········································································································ 1分 解不等式②得x?3 ················································································································ 2分 ····················································································· 3分 ?原不等式组的解集为：0≤x?3 · -3 -2 -1 0 1 2 3 x ················································································································································· 4分 20．（本小题满分7分） 解：（1）1?15%?5%?20%?25%?17%?18%，（无计算过程不扣分） 喜欢足球运动的人数最多 ······································································································· 2分 （2）结合喜欢篮球运动的人数及所占比例可得： ············································································ 3分 (20?40)?20%?300 样本容量为300 ··············································································· 5分 300?18?20?34（如图补全条形图） ·（各1分，若没有计算过程，图形正确也给满分） （3）3900?最喜欢该球类运动的人数/人 60 50 40 30 20 10 34 男同学 女同学 羽毛球 第20题图 运动项目 20·········································· 7分 ?260（人）喜欢乒乓球的女生有260人． ·30021．（本小题满分6分） （1）列表： 或树状图： 一 二 ?2 ?1 1 开始 ?2 ?1 (?2，?2) (?1，?2) (?2，?1) (?1，?1) (?2，1) (?11)， (1，?2) (1，?1) (11)， ?2 ?1 1 ?2 ?1 1 ?2 ?1 1 ?2 ?1 1 1 ···················································· 3分 4． ··································································································· 4分 91（2）方案二：P（中奖）?． ·························································································· 5分 3方案一：P（中奖）?应该选择方案一，因为方案一的中奖机会大． ····································································· 6分 22．（本小题满分8分） 解法一：（1）四边形ACED是等腰梯形． ··········································································· 1分 证明：?四边形ABCD是矩形， ?△ACE≌△ACB≌△CAD E ··························· 2分 ??1??2，AD?CE，CD?AE ·4 D 3 C 又?OA?OC，?OE?OD，??3??4 ················ 3分 O 2 ······ 4分 ??DOE??AOC，??1??4，?DE∥AC ·?四边形ACED是等腰梯形． 1 （2）在Rt△OEC中，设EO?x， B A 则x?3?(4?x) ························································ 5分 222第22题图 ?x?7 ··································································································································· 6分 87DE由△ODE∽△OCA，得8? ······································································ 7分 2273?44?8