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已知Rt△ABC中,∠C=90°,AC=2,BC=3,那么下列各式中,正确的是(...
已知Rt△ABC中,∠C=90°,AC=2,BC=3,那么下列各式中,正确的是( )
A.sinB=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662019_ST/0.png)
B.cosB=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662019_ST/1.png)
C.tanB=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662019_ST/2.png)
D.cotB=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662019_ST/3.png)
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直角三角形纸片的两直角边AC与BC之比为3:4.
(1)将△ABC如图1那样折叠,使点C落在AB上,折痕为BD;
(2)将△ABD如图2那样折叠,使点B与点D重合,折痕为EF.
则tan∠DEA的值为( )
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A.
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B.
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C.
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D.
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在△ABC中,∠C=90°,BC=3,AB=4,则下列结论正确的是( )
A.sinA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662017_ST/0.png)
B.cosA=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662017_ST/1.png)
C.tanA=
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D.cotA=
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在Rt△ABC中,∠C=90°,AB=5,AC=4,则cosB的值等于( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662016_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662016_ST/1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662016_ST/2.png)
D.
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在Rt△ABC中,∠C=90°,若AB=5,BC=3,则cosB=( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662015_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103101402570766219/SYS201311031014025707662015_ST/1.png)
C.
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D.
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三角形在正方形网格纸中的位置如图所示.则sinα的值是( )
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A.
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B.
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C.
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D.
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