设直线l与抛物线y
2=2px(p>0)交于A,B两点,已知当直线l经过抛物线的焦点且与x轴垂直时,△OAB的面积为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100716252808108/SYS201311031007162528081021_ST/0.png)
(O为坐标原点).
(1)求抛物线的方程;
(2)当直线l经过点P(a,0)(a>0)且与x轴不垂直时,若在x轴上存在点C,使得△ABC为正三角形,求a的取值范围.
考点分析:
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,求平面PBE与平面ABCD所成的二面角的大小.
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已知数列{a
n}的首项a
1=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100716252808108/SYS201311031007162528081018_ST/0.png)
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,其中n∈N
+.
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}为等比数列;
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,若S
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在△ABC中,角A,B,C所对的边分别为a,b,c,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100716252808108/SYS201311031007162528081017_ST/0.png)
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已知O是△ABC的外心,AB=2,AC=1,∠BAC=120°.设
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131103100716252808108/SYS201311031007162528081016_ST/0.png)
=
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=
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=m
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,则m-n=
.
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