2012-2013学年度潍坊市奎文区初中学段第一学期八年级期末考试数学试题参考答案
一、选择题
1-5 CBABC 6-10 DBCDB 11-12 AA
二、填空题
13．![](https://wkrtcs.bdimg.com/rtcs/image?w=36.2&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"36.2","h":"21.733333333333","dataType":"gif","c":"word/media/image1.png"})
等，答案不唯一
14．![](https://wkrtcs.bdimg.com/rtcs/image?w=42.533333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"42.533333333333","h":"17.2","dataType":"gif","c":"word/media/image3.png"})
15．![](https://wkrtcs.bdimg.com/rtcs/image?w=41.666666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"41.666666666667","h":"17.2","dataType":"gif","c":"word/media/image4.png"})
16．![](https://wkrtcs.bdimg.com/rtcs/image?w=41.666666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"41.666666666667","h":"24.466666666667","dataType":"gif","c":"word/media/image5.png"})
17．![](https://wkrtcs.bdimg.com/rtcs/image?w=74.266666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"74.266666666667","h":"38.933333333333","dataType":"gif","c":"word/media/image6.png"})
三、解答题
18．①![](https://wkrtcs.bdimg.com/rtcs/image?w=37.133333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"37.133333333333","h":"19.933333333333","dataType":"gif","c":"word/media/image7.png"})
② ③ ④是增根，原方程无解．
19．略
20．解：原式=![](https://wkrtcs.bdimg.com/rtcs/image?w=163.93333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"163.93333333333","h":"38.933333333333","dataType":"gif","c":"word/media/image11.png"})
解不等式组得：![](https://wkrtcs.bdimg.com/rtcs/image?w=65.2&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"65.2","h":"17.2","dataType":"gif","c":"word/media/image12.png"})
选取的数字在的范围内不为5，，0即可（答案不唯一），代入求值略．
21．解：（1） 3，5
（2）26 25 24
（3）不能 ![](https://wkrtcs.bdimg.com/rtcs/image?w=6.3333333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"6.3333333333333","h":"0.93333333333333","dataType":"png","c":"word/media/image2.png","imgOriW":645,"imgOriH":62})
因为此时众数26万元>中位数25万元．
（或：因为从统计表中可知20名营业员中，只有9名达到或超过目标，不到半数）
22．（1）在Rt△ACB中，![](https://wkrtcs.bdimg.com/rtcs/image?w=216.46666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"216.46666666667","h":"22.666666666667","dataType":"gif","c":"word/media/image14.png"})
∴AC=2
（2）∵BD=0.5
∴CD=2
在Rt△ECD中，![](https://wkrtcs.bdimg.com/rtcs/image?w=228.2&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"228.2","h":"22.666666666667","dataType":"gif","c":"word/media/image15.png"})
∴EC=1.5
∴![](https://wkrtcs.bdimg.com/rtcs/image?w=175.66666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"175.66666666667","h":"17.2","dataType":"gif","c":"word/media/image16.png"})
答：梯子顶端下滑了0.5米
23．解：设![](https://wkrtcs.bdimg.com/rtcs/image?w=11.8&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"11.8","h":"13.6","dataType":"gif","c":"word/media/image17.png"})
人
![](https://wkrtcs.bdimg.com/rtcs/image?w=127.66666666667&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"127.66666666667","h":"45.266666666667","dataType":"gif","c":"word/media/image18.png"})
解得![](https://wkrtcs.bdimg.com/rtcs/image?w=69.733333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"69.733333333333","h":"17.2","dataType":"gif","c":"word/media/image19.png"})
为整数，至少40名，最多43人
24．（1）∵∠B与∠C的平分线交于点O
∴∠ABO=∠CBO,∠ACO=∠BCO
∵BE=OE
∴∠ABO=∠BOE
∴∠BOE=∠CBO
∴EF∥BC
∴∠COF=∠BCO=∠ACO
∴OF=CF
（2） ∵BE=OE，OF=CF
∴△AEF的周长=AE+AF+EO+OF=AE+AF+EB+CF=AB+AC
（3） ∵△ABC的周长比△AEF的周长大12cm
∴AB+AC+BC-（AE+EF+AF）=12
∵EF=OE+OF=BE+CF
∴BC=12
∵O在∠ABC平分线上，O到AB的距离为4![](https://wkrtcs.bdimg.com/rtcs/image?w=21.733333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"21.733333333333","h":"13.6","dataType":"gif","c":"word/media/image20.png"})
∴O到CB的距离为4
∴S△BCO=![](https://wkrtcs.bdimg.com/rtcs/image?w=16.333333333333&md5sum=8cb3641e01832e0310c47f30728ff7af&sign=a2bbda72cc&rtcs_flag=1&rtcs_ver=3.1&l=webapp&bucketNum=47&ipr={"t":"img","w":"16.333333333333","h":"38.933333333333","dataType":"gif","c":"word/media/image21.png"})
×12×4=24
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