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如图,把菱形ABCD沿对角线AC的方向移动到菱形A′B′C′D′的位置,它们的重...
如图,把菱形ABCD沿对角线AC的方向移动到菱形A′B′C′D′的位置,它们的重叠部分(图中阴影部分)的面积是菱形ABCD面积的
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/0.png)
,若AC=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/1.png)
,则菱形移动的距离AA′是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/images2.png)
A.1
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/2.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/3.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139008_ST/4.png)
考点分析:
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化简
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/0.png)
,甲,乙两同学的解法如下:
甲:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/1.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/2.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/3.png)
-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/4.png)
.
乙:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/5.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/6.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/7.png)
-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139007_ST/8.png)
.
对于甲,乙两同学的解法,正确的判断是( )
A.甲,乙解法都正确
B.甲正确,乙不正确
C.甲,乙都不正确
D.乙正确,甲不正确
查看答案
已知不等腰三角形三边长为a,b,c,其中a,b两边满足
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139006_ST/0.png)
,那么这个三角形的最大边c的取值范围是( )
A.c>8
B.8<c<14
C.6<c<8
D.8≤c<14
查看答案
若a+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139005_ST/0.png)
=1,则a的取值范围是( )
A.a=0
B.a=1
C.a=0或a=1
D.a≤1
查看答案
甲、乙两同学近期5次百米跑测试成绩的平均数相同,甲同学成绩的方差S
2甲=4,乙同学成绩的方差S
2乙=3.1,则对他们测试成绩的稳定性判断正确的是( )
A.甲的成绩较稳定
B.乙的成绩较稳定
C.甲、乙成绩的稳定性相同
D.甲、乙成绩的稳定性无法比较
查看答案
样本方差的计算式S
2=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588213922/SYS201311030008555882139003_ST/0.png)
[(x
1-30)
2+(x
2-30)
2+…+(x
n-30)
2]中,数字90和30分别表示样本中的( )
A.众数、中位数
B.方差、标准差
C.样本中数据的个数、平均数
D.样本中数据的个数、中位数
查看答案