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△ABC中,sin2A=sin2B+sin2C,则△ABC为( ) A.直角三...
△ABC中,sin2A=sin2B+sin2C,则△ABC为( )
A.直角三角形
B.等腰直角三角形
C.等边三角形
D.等腰三角形
考点分析:
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若α、β终边关于y轴对称,则下列等式成立的是( )
A.sinα=sinβ
B.cosα=cosβ
C.tanα=tanβ
D.sinα=-sinβ
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将函数
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的图象向左平移
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个单位,再向上平移2个单位,则所得图象的函数解析式是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123713132691389/SYS201310251237131326913005_ST/2.png)
B.
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C.
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D.y=cos2
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α是第四象限角,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123713132691389/SYS201310251237131326913004_ST/0.png)
,则sinα=( )
A.
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B.
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C.
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D.
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如图曲线对应的函数是( )
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A.y=|sinx|
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要测量底部不能到达的电视塔AB的高度,在C点测得塔顶A的仰角是45°,在D点测得塔顶A的仰角是30°,并测得水平面上的∠BCD=120°,CD=40m,则电视塔的高度为( )
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A.10
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m
D.40m
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