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制作一个圆锥模型,其侧面是用一个半径为9cm,圆心角为240°的扇形铁皮围成的,...
制作一个圆锥模型,其侧面是用一个半径为9cm,圆心角为240°的扇形铁皮围成的,则圆锥底面半径为( )
A.4cm
B.3cm
C.6cm
D.12cm
考点分析:
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设a=
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-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164825771526638/SYS201310221648257715266011_ST/1.png)
,b=
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-1,c=
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,则a、b、c之间的大小关系是( )
A.c>b>a
B.a>c>b
C.b>a>c
D.a>b>c
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已知点P的坐标为(x,y)且
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164825771526638/SYS201310221648257715266010_ST/0.png)
,则点P关于原点的对称点P′的坐标是( )
A.(-1,
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)
B.(-1,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164825771526638/SYS201310221648257715266010_ST/2.png)
)
C.(1,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164825771526638/SYS201310221648257715266010_ST/3.png)
)
D.(1,
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)
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观察下列方程:①x+
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=3,②x+
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=5,③x+
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