已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/[cos(π/4)+x] 已知0<β<π/2<α<π,cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 求cos(α+β) 已知α,β∈(0,π)且tan(α-β)=1/2,ta

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已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/[cos(π/4)+x] 已知0<β<π/2<α<π,cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 求cos(α+β) 已知α,β∈(0,π)且tan(α-β)=1/2,ta

已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/[cos(π/4)+x] 已知0<β<π/2<α<π,cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 求cos(α+β) 已知α,β∈(0,π)且tan(α-β)=1/2,ta
已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+
已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/[cos(π/4)+x] 已知0<β<π/2<α<π,cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 求cos(α+β) 已知α,β∈(0,π)且tan(α-β)=1/2,tanβ=-1/7.求2α-β

已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/[cos(π/4)+x] 已知0<β<π/2<α<π,cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 求cos(α+β) 已知α,β∈(0,π)且tan(α-β)=1/2,ta
1.∵sin[(π/4)-x)]=5/13,0<x<π/4 ∴cos[(π/4)-x)]=12/13 cos2x=cos[(π/2)-2x]=2sin[(π/4)-x)]*cos[(π/4)-x)]=2×5/13×12/13=120/169 cos[(π/4)+x]=sin[π/2-(π/4+x)]=sin(π/4-x)=5/13 ∴cos2x/cos[(π/4)+x]=120/169 /5/13 =24/13 2.∵0<β<π/2<α<π 又∵cos[α-(β/2)]=-1/9,sin[(α/2)-β]=2/3 ∴sin[α-(β/2)]=根号80/9,cos[(α/2)-β]=根号5/3 ∴sin[(α+β)/2]=sin{[α-(β/2)]-[(α/2)-β]}=sin[α-(β/2)]cos[(α/2)-β]－sin[(α/2)-β]cos[α-(β/2)]=22/27 cos[(α+β)/2]=根号75/27 cos(α+β)=-根号239/27 3.∵tan(α-β)=1/2 ∴tan(2α-2β)=4/3 ∴tan(2α-β)=tan(2α-β+β)=1 ∵α,β∈(0,π)且tan(α-β)=1/2,tanβ=-1/7 ∴β∈(π/2,π),α∈(0,π/4),∴2α-β∈(-π,0) ∴2α-β=-3π/4 你要给我加分,太难打了!

已知sin(π/4--x)=5/13,0 已知sin(π/4-x)=5/13,且0 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2(π/3-x) 已知sin(π/4+x)=12/13(π/4 已知sin(π/4-x)=12/13,0 已知sin(π/4-x)=12/13,0 已知sin(x+π)=4/5,且sinxcosx 已知sin(TT/4+x)=5/13,0 已知函数f(x)=(1+1 anx)sin^2x+m sin(x+π/4)sin(x-π/4) 已知-π/2＜x＜0,sin x+cos x=1/5求sin 2x+2 sin 已知sin(π/2-x)+sin(π-x)/cos(-x)+sin(2π-x)=2009,则tan(x+5π/4)等于?已知sin(π/2-x)+sin(π-x)/cos(-x)+sin(2π-x)=2009,则tan(x+5π/4)等于（） A.-2009 B.-1/2009 C.1/2009 D.2009 已知sinα（x+π/6）=1/4,则sin（5π/6-x）+sin（π/3-x）的平方=? 已知sin(x+6/π)=4/1,求sin(6/5π-x)+sin^2(3/π-x)的值 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin方(π/3-x)的值 已知sin(x+π/6)=1/4,求sin(5π/6-x)+sin^2（11π/6-x）如题, 已知sin(x+π/6)=1/3,求sin(5π/6-x)+sin^2(π/3-x) 已知函数f(x)=cos2x/[sin(π/4-x)] 已知 Sin(X+ 派/6)=1/4求 Sin(5/6派 - X)+Sin^2 (派/3 -X)