sin(π/4+α)sin(π/4-α)=1/4 求2sin^2(a) -1+tana-1/tan

证明(2-2sin(α+3/4π)cos(α+π/4))/cos^4α-sin^4α=1=tanα/1-tana 已知sin(π/4+2a)sin(π/4-2a)=1/4,a∈（π/4,π/2)求2sin方a+tana-cota-1 函数f(x)=(1+1/tanx)sin^2x-2sin(x+π/4)sin(x-π/4).若tana=2,求f(a). 已知函数f(x)=(1+1/tanx)sin^2-2sin(x+π/4)sin(x-π/4).求tana=2时,f(a) 已知tan{π/4+a}=3,求sina*sin(3π /2 +a)-sin^2a+1的值 已知sin(π/4+α)*sin(π/4-α)=1/4,α∈(π/4,π/2),求2sin^α+tanα-cotα-1的 已知tan(A-B)/tanA+sin^2C/sin^2A=1,求证：tanA*tanB=tan^2C 已知tan(a-r)/tana+sin^2b/sin^2a=1 ,求证tan^2b=tana*tanr.. 已知cosa=1/4,求sin(2π+a)cos(-π+a)/cos(-a)tana 1.已知tana=1/3,tanb=-1/4求tan(2a-2b).2.已知sin(a+π/6)=1/3求sin(π/6 已知tan(π/4+α)=2,tanβ=1/2.⑴求tanα的值,⑵求sin(α+β)-2sinαcosβ/2sinαc 一道高中三角函数题tanα/tanα-1=2,求下列各式的值.sinα-3cosα/sinα+cosα4sin²