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已知smθ=,那么cos2θ=
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高一下学期数学《》真题及答案
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化简=
cosα
﹣cosα
cos2α
﹣cos2α
下列公式是正确的
sin 2α+cos2α=1
sin 2α-cos2α=1
sin 2α+cos2α=-1
sin 2α-cos2α=-1
化简=
cosα
﹣cosα
cos2α
﹣cos2α
已知cosα=﹣则cos2α=.
已知fx=x2+sinθ﹣cosθx+sinθθ∈R.的图象关于y轴对称则sin2θ+cos2θ的值
2
1
下列公式是正确的
sin 2α= 2sin α cos α
sin 2α= cos2α-sin 2α
sin 2α= 21(1+ cos2 α)
sin 2α= 21(1- cos2 α)
设全集U=R则A∩B=
(cos2,1]
[cos2,1]
(﹣1,2)
(﹣1,cos2]
已知sinα+cosβ=则cos2α+cos2β的取值范围是.
已知α为第四象限角且cosα﹣|sinα﹣cosα|=﹣求tanαsin2αcos2α的值.
已知角α的顶点与原点重合始边与x轴的正半轴重合终边上一点的坐标为34则cos2α=________.
已知等式cosα•cos2α=cosα•cos2α•cos4α=请你写出一个具有一般性的等式使你写
已知α为第二象限角sinα+cosα=则cos2α=________.
已知cosα=﹣则cos2α=.
已知sinα=+cosα且α∈0则sin2α=cos2α=.
要证明sin4θ-cos4θ=2sin2θ-1过程为sin4θ-cos4θ=sin2θ+cos2θs
分析法
反证法
综合法
间接证明法
已知αβ∈0π且tanα=2cosβ=-.1求cos2α的值2求2α-β的值
下列公式是正确的
sin2 α= 2sin α? cos α
sin2 α= 21(1- cos2 α)
sin2 α= 21(1+ cos2 α)
sin2 α= 21sin αcosα
双扭线r=2acos2θ所围成图形的面积是
4a
cos2θdθ
4a
cos2θdθ
2a
cos2θdθ
已知cos的值则cos2的值为
1 2cos2
1 2cos
1 cos2
2 cos2
已知α为第二象限角则cos2α=.
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