满分5 >
高中数学试题 >
在空间四边形ABCD中,AC和BD为对角线,G为△ABC的重心,E是BD上一点,...
在空间四边形ABCD中,AC和BD为对角线,G为△ABC的重心,E是BD上一点,BE=3ED,以{
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281017_ST/0.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281017_ST/1.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281017_ST/2.png)
}为基底,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281017_ST/3.png)
=
.
考点分析:
相关试题推荐
过点M(3,-1)且被点M平分的双曲线
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281016_ST/0.png)
的弦所在直线方程为
.
查看答案
已知向量{
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/0.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/1.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/2.png)
}是空间的一个基底,从
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/3.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/4.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/5.png)
中选择向量
,可以与向量P=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/6.png)
-2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/7.png)
,q=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/8.png)
+2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281015_ST/9.png)
构成空间的一个基底.
查看答案
命题“若a,b都是奇数,则a+b是偶数”的逆否命题是
.
查看答案
已知约束条件
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281013_ST/0.png)
,目标函数z=3x+y,某学生求得x=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281013_ST/1.png)
,y=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281013_ST/2.png)
时,z
max=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225344155728172/SYS201311012253441557281013_ST/3.png)
,这显然不合要求,正确答案应为x=
; y=
; z
max=
.
查看答案
在△ABC中,a=3,b=7,c=5,则cosB=
.
查看答案