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已知在△ABC中,点D、E、F分别在边AB、AC和BC上,且DE∥BC,DF∥A...
已知在△ABC中,点D、E、F分别在边AB、AC和BC上,且DE∥BC,DF∥AC,那么下列比例式中,正确的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651005_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651005_ST/1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651005_ST/2.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651005_ST/3.png)
考点分析:
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如果
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是非零向量,那么下列等式正确的是( )
A.
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=
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B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651004_ST/3.png)
=
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C.
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+
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=0
D.
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+
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=0
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将二次函数y=x
2的图象向右平移1个单位,那么得到的图象对应的函数表达式为( )
A.y=x
2-1
B.y=x
2+1
C.y=(x-1)
2D.y=(x+1)
2
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如果二次函数y=ax
2+bx+c的图象如图所示,那么下列判断中,不正确的是( )
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A.a>0
B.b<0
C.c>0
D.abc>0
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在Rt△ABC中,∠C=90°,∠A、∠B、∠C所对的边分别为a、b、c,下列等式中不一定成立的是( )
A.b=atanB
B.a=ccosB
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651001_ST/0.png)
D.a=bcosA
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如图,下列角中为俯角的是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022160539761665175/SYS201310221605397616651000_ST/images0.png)
A.∠1
B.∠2
C.∠3
D.∠4
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