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在△ABC中,已知AC=3,BC=4,AB=5,那么下列结论成立的是( ) A....
在△ABC中,已知AC=3,BC=4,AB=5,那么下列结论成立的是( )
A.sinA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023012_ST/0.png)
B.cosA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023012_ST/1.png)
C.tanA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023012_ST/2.png)
D.cotA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023012_ST/3.png)
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在Rt△ABC中,∠C=90°,AC=3,BC=4,那么cosB的值是( )
A.
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B.
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C.
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D.
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在Rt△ABC中,∠C=90°,a,b,c分别是∠A,∠B,∠C的对边,下列关系式中错误的是( )
A.b=c•cosB
B.b=a•tanB
C.a=c•sinA
D.a=b•cotB
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在△ABC中,∠C=90°,如果tanA=
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,那么sinB的值等于( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023009_ST/1.png)
B.
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C.
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D.
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在Rt△ABC中,∠C=90°,a=4,b=3,则sinA的值是( )
A.
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B.
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C.
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D.
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如图,菱形ABCD的对角线AC=6,BD=8,∠ABD=α,则下列结论正确的是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103102712452502311/SYS201311031027124525023007_ST/images0.png)
A.sinα=
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B.cosα=
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C.tanα=
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D.tanα=
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