若cosα=2m-1(α为锐角),则m的取值范围是 .
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如图,在直角坐标系中,将矩形OABC沿OB对折,使点A落在A
1处,已知OA=
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,AB=1,则点A
1的坐标是( )
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A.(
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)
B.(
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)
C.(
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)
D.(
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)
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在△ABC中,∠C=90°,BC=2,sinA=
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,则边AC的长是( )
A.
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B.3
C.
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D.
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在△ABC中,∠C=90°,AB=2,AC=1,则sinB的值是( )
A.
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B.
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C.
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D.2
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tan30°的值等于( )
A.
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B.
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C.
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D.
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若
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cot(A+10°)-3=0,则∠A的值为( )
A.40°
B.50°
C.20°
D.70°
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