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如图,在四棱锥P-ABCD中,底面ABCD为平行四边形,∠ADC=45°,AD=AC=1,O为AC的中点,PO⊥平面ABCD,PO=2,M为PD的中点.
(1)证明:PB∥平面ACM;
(2)证明:AD⊥平面PAC.
考点分析:
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已知函数
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.
(Ⅰ)求f(x)的最小正周期:
(Ⅱ)求f(x)在区间
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上的最大值和最小值.
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如图,F
1,F
2分别是双曲线C:
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100756724435368/SYS201311031007567244353014_ST/0.png)
-
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=1(a,b>0)的左、右焦点,B是虚轴的端点,直线F
1B与C的两条渐近线分别交于P,Q两点,线段PQ的垂直平分线与x轴交与点M,若|MF
2|=|F
1F
2|,则C的离心率是
.
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已知双曲线
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100756724435368/SYS201311031007567244353013_ST/0.png)
和椭圆
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有相同的焦点,且双曲线的离心率是椭圆离心率的两倍,则双曲线的方程为
.
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已知
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100756724435368/SYS201311031007567244353012_ST/0.png)
,则当m•n取得最小值时,椭圆
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的离心率为
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已知正四棱柱ABCD-A
1B
1C
1D
1中,AA
1=2AB,E为AA
1中点,则异面直线BE与CD
1所形成角的余弦值为
.
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