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如图,等边△ABC绕点B逆时针旋转30°时,点C转到C′的位置,且BC′与AC交...
如图,等边△ABC绕点B逆时针旋转30°时,点C转到C′的位置,且BC′与AC交于点D,则
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638012_ST/0.png)
的值为
.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638012_ST/images1.png)
考点分析:
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若记y=f(x)=
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,其中f(1)表示当x=1时y的值,即f(1)=
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)表示当x=
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时y的值,即f(
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;…;则f(1)+f(2)+f(
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)+f(3)+f(
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)+…+f(2011)+f(
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)=
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有一列数:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638008_ST/0.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638008_ST/1.png)
,
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,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638008_ST/3.png)
…,则它的第7个数是
;第n个数是
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已知:二次函数y=ax
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![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101185906706963891/SYS201311011859067069638007_ST/images0.png)
A.①⑤
B.①②⑤
C.②⑤
D.①③④
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