若sinα=1/2,则sin(π/4-α)cos(π/4-α)=

若sin^2β-sin^2α=m,则sin(α+β)sin(α-β) 若sinα=1/2,则sin(π/4-α)cos(π/4-α)= 若sin(α+β)=1/2,sinαcosβ=3/4,则sin(α-β)= 若sin (π/4+α)sin(π/4-α)=-1/8,则2sin²α+tanα-1/tanα-1的值为 若sin^2α+sinα=1 则cos^4α+cos^2α= sin(π/6-α)=1/4,则sin(π/6+2α)= 若sinαsinβ+cosαcosβ=0,则sinαcosα+sinβcosβ= .1若sinαsinβ+cosαcosβ=0,则sinαcosα+sinβcosβ= 2已知sin(α+β)=1,则cos(α+2β)+sin(2α+β)=急, 化简sin(α+β)+sin(α-β)+2sinαsin(3π/2-β)= sin(π-α)=-2sin(π/2+α),则sinαcosα等于 已知sin(3π-α)=-2sin(π/2+α)则sinαcosα sin(π/4+α)sin(π/4-α)=1/4 求2sin^2(a) -1+tana-1/tan 若sinβ=1/3,sin(α+β)=1,则sin(2α+β)=? 若（sinα+cosα）/（sinα-cosα）=2 则sin(α-5π)·sin(3π/2-α)=? 若sinα+cosα/sinα-cosα=2,则sin(α-5π）*sin（3π/2-α）等于? 2sinα-3cosα/4sinα-9cosα=-1,则9sin^2α-3sinαcosα-5= 若sin(π+α)+sin(-α)=-m,则sin（3π+a)+2sin(2π-a)的值为? 已知3sin²α+2sin²β=2sinα,求cos²α+cos²β的取值范围已知3sin²α+2sin²β=2sinα则有2sin²β=2sinα-3sin²α即sin²β=sinα-1.5sin²α所以cos²β=1-sin²β=1-(sinα-1.5sin²α)=1- 若2sin(π/4+α)=sinθ+cosθ,2sin²β=sin2θ,求证:sin2α+1/2cos2β=0