已知sin(π/4--x)=5/13,0<x<π/4,求sin2π/cos(π/4--x)的值
已知sin(π/4--x)=5/13,0<x<π/4,求sin2π/cos(π/4--x)的值
已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+
已知0<A<π/2<B<π,cos(B-π/4)=1/3,sin(A+B)=4/5求cos(a+
已知tan2x=-2 π/2<2x<π求[2cos^2(x/2)-sinx-1]/根号2sin(π/4+x)
已知√3sinα-cosα=4m-6(0<α<π),求m的取值范围
已知π/4<a<b<π/2,且sin(a+b)=4/5,cos(a-b)=12/13
已知sin2α=3/5,α∈(5π/4,3π/2),求cosα的值及求满足sin(α-x)-sin(α+x)+2cosα
已知tan(a+π/4)=-1/2,π/2<a<π,求(sin2a-2cos^2a)/√2sin(a-π/4
(已知0<α<π,tanα=-2) 求2sin²α-sinαcosα+cos²α 求老师
已知sin(x-π/4)cos(x-π/4)=-1/4,求cos4x的值.
已知cos(π/4+x)=5/13,0<x<π/4,求sin(π/4-x)/cos2x
已知sin(π/4-x)=5/13,x属于(0,π/4),求(cos2x)/cos[(π/4)+x]