sin(α+2/5π)化简成sin(2/π+α)为什么
1/2sin α cos α 为什么等于sin α
若(sinα+cosα)/(sinα-cosα)=2 则sin(α-5π)·sin(3π/2-α)=?
若sinα+cosαsinα−cosα=2,则sin(α-5π)•sin(3π2-α)等于( )
已知sin(α-β)=3/5,sin(α+β)=-3/5,π/2
求证:sin(2α+β)sinα
1.证明 cos(α-π/2)=sinα sin(α-π/2)=﹣sinα
已知sin(3π−α)=−2sin(π2+α),则sinαcosα=( )
已知sin(2α+ β)=5sinβ,求证:2sin(α+ β)=3sinα
1)tan(3π-α)/sin(π-α)sin(3/2π-α)+sin(2π-α)cos(α-7/2π)/sin(3/2
已知tanα=2,sinα+cosα<0,求[sin(2π-α)*sin(π+α)*cos(-π+α)]/[sin(3π
已知cos(π+α)=1/2,计算sin(2π-α) sin[(2n+1)π+α]+sin[α-(2n+1)π]/sin
α属于(0,π/2)且2sin²α-sinαcosα-3cos²α=0求sin(α+π/4)/sin