满分5 >
初中数学试题 >
如图,在Rt△ABC中,∠ACB=90°,∠A=30°,CD⊥AB于点D.则△B...
如图,在Rt△ABC中,∠ACB=90°,∠A=30°,CD⊥AB于点D.则△BCD与△ABC的周长之比为( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371009_ST/images0.png)
A.1:2
B.1:3
C.1:4
D.1:5
考点分析:
相关试题推荐
如图,在直角坐标系中,点A是x轴正半轴上的一个定点,点B是双曲线y=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371008_ST/0.png)
(x>0)上的一个动点,当点B的横坐标逐渐增大时,△OAB的面积将会( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371008_ST/images1.png)
A.逐渐增大
B.不变
C.逐渐减小
D.先增大后减小
查看答案
若一个所有棱长相等的三棱柱,它的主视图和俯视图分别是正方形和正三角形,则左视图是( )
A.矩形
B.正方形
C.菱形
D.正三角形
查看答案
10名同学分成甲、乙两队进行篮球比赛,它们的身高(单位:cm)如下表所示:
| 队员1 | 队员2 | 队员3 | 队员4 | 队员5 |
甲队 | 177 | 176 | 175 | 172 | 175 |
乙队 | 170 | 175 | 173 | 174 | 183 |
设两队队员身高的平均数依次为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/0.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/1.png)
,身高的方差依次为S
甲2,S
乙2,则下列关系中完全正确的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/2.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/3.png)
,S
甲2>S
乙2B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/4.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/5.png)
,S
甲2<S
乙2C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/6.png)
>
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/7.png)
,S
甲2>S
乙2D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/8.png)
<
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371006_ST/9.png)
,S
甲2>S
乙2
查看答案
下列图形中既是中心对称图形又是轴对称图形的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371005_ST/images0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371005_ST/images1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371005_ST/images2.png)
D.
查看答案
函数
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185743849837103/SYS201311011857438498371004_ST/0.png)
中自变量x的取值范围是( )
A.x≤2
B.x=3
C.x<2且x≠3
D.x≤2且x≠3
查看答案