![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183016_ST/images0.png)
如图,平行四边形ABCD中,CD=1,∠BCD=60.,且BD⊥CD,正方形ADEF和平面ABCD成直二面角,G,H是DF,BE的中点.
(Ⅰ)求证:BD⊥平面CDE;
(Ⅱ)求证:GH∥平面CDE;
(Ⅲ)求三棱锥D-CEF的体积.
考点分析:
相关试题推荐
在等比数列{a
n}中,a
n>0,(n∈N
*),公比q∈(0,1),且a
1a
5+2a
3a
5+a
2a
8=25,a
3与a
5的等比中项为2.
(1)求数列{a
n}的通项公式;
(2)设b
n=log
2a
n,数列{b
n}的前n项和为S
n,当
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183015_ST/0.png)
最大时,求n的值.
查看答案
如图,设A是单位圆和x轴正半轴的交点,P,Q是单位圆上两点,O是坐标原点,且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183014_ST/0.png)
,∠AOQ=α,α∈[0,π).
(Ⅰ)若点Q的坐标是
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183014_ST/1.png)
,求
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183014_ST/2.png)
的值;
(Ⅱ)设函数
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183014_ST/3.png)
,求f(α)的值域.
查看答案
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183013_ST/images0.png)
如图,n
2(n≥4)个正数排成n行n列方阵:符号a
ij(1≤i,j≤n)表示位于第i行第j列的正数.已知每一行的数成等差数列,每一列的数成等比数列,且各列数的公比都等于q.若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183013_ST/0.png)
,a
24=1,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183013_ST/1.png)
,则q=
,a
ij=
.
查看答案
如图,水平放置的三棱柱的侧棱长和底边长均为2,且侧棱AA
1⊥面A
1B
1C
1,正视图是边长为2的正方形,俯视图为一个等边三角形,该三棱柱的左视图面积为
.
查看答案
在△ABC中,内角A,B,C的对边分别是a,b,c,若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183011_ST/0.png)
,sinC=2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101222351920418377/SYS201311012223519204183011_ST/1.png)
sinB,则A角大小为
.
查看答案