已知0<α<π/2<β<π,cos(β-π/4π)=1/3,sin(α+β)=4/5,sin2β=-7/9.cos(α+
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已知0<α<π/2<β<π,cos(β-π/4π)=1/3,sin(α+β)=4/5,sin2β=-7/9.cos(α+π/4)的值
cos(β-π/4)=1/3 cos2(β-π/4)=2[cos(β-π/4)]^2-1=-7/9 cos(2β-π/2)=-7/9 cos(π/2-2β)=-7/9 sin2β=-7/9 cos(β-π/4)=1/3,sin(α+β)=4/5,0<α<π/2<β<π sin(β-π/4)=2√2/3 cos(α+β)=-3/5 cos(α+π/4)=cos[(α+β)+(π/4-β)] =cos(α+β)cos(π/4-β)-sin(α+β)sin(π/4-β) =cos(α+β)cos(β-π/4)+sin(α+β)sin(β-π/4) =(8√2-3)/15
已知0<α<π/2<β<π,cos(β-π/4π)=1/3,sin(α+β)=4/5,sin2β=-7/9.cos(α+
已知π/2<β<α<3π/4,cos(α-β)=12/13,sin(α+β)=-3/5 求sin2α的值
1.已知sin2α=1/4,α属于(π/4,π/2),则 cosα-sinα=?2.已知sinα+cosα=1/3,0<
已知sinα+cosα=三分之根号二,sinα-cosα=-4/3,且α∈(-π/2,0),计算(1+sin2α+cos
已知:0<α<π/2<β<π,cos﹙β-π/4﹚=1/3,sin(α+β)=4/5 1,求sin2β的值
已知α∈(0,π/2),且2sinα-sinαcosα-3cosα=0.求[sin(α+π/4)]/[sin2α+cos
已知π/2<β<α<3π/4,且cos( α-β)=12/13,cos(α+β)=-4/5,求sin2α
已知sin2α=1/4,且π/2<2α<π,则cosα-sinα=
若sin(π/4+α)=sinθ+cosθ,2sin^2β=sin2θ,求证:sin2θ+2cos2β=3
已知cosα-sinα=3√5/5,17π/12<α<7π/4,求sin2α和tan(π/4+α)
已知α∈(π/4,π/2)若sin2α=3/5则sinα-cosα=
已知sin2α+cosα=3√5/5,α∈(0,π/4),sin(β-π/4)=3/5,β∈(π/4,π/2)