已知0<β<π/4,π/4<α<3π/4,cos(π/4-α)=3/5,sin(3π/4+β)=5/13,求sin(α+
已知sin(α-β)cosα-cos(β-α)sinα=3/5,β是第三象限角,求sin(β+5π/4)的值
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已知α∈(0,π/2),且2sin²α-sinαcosα-3cos²α=0,求[sin(α+π/4)
已知0<β<π/4,π/4<α<3π/4,cos(π/4-α)=3/5,sin(3π/4+β)=5/13,求sin(α+
已知tan(α+π/4)=3,求cosα+2sinα/cosα-sinα的值
α属于(0,π/2)且2sin²α-sinαcosα-3cos²α=0求sin(α+π/4)/sin
已知α∈(0,π/2),且2sinα-sinαcosα-3cosα=0.求[sin(α+π/4)]/[sin2α+cos
已知tanα=2,sinα+cosα<0,求[sin(2π-α)*sin(π+α)*cos(-π+α)]/[sin(3π
已知0<α<π/2<β<π,sinα=3/5,cos(α+β)=-4/5求cosβ
已知 cos π/5 =(根号5 +1)/4 求 sin π/5,sin -π/5 ,sin 4π/5 ,sin 3π/
已知cosα+cosβ=3/5sinα+sinβ=4/5求cos(α-β)