1-2sin²π/8=sinπ/4
已知函数fx=(1+1/tanx)sin^x-2sin(x+π/4)sin(x-π/4)
α属于(0,π/2)且2sin²α-sinαcosα-3cos²α=0求sin(α+π/4)/sin
1.已知sin(π/6-x)=1/4,sin(π/6+2x)=?
求证:1-2sinαcosα/cos²α-sin²α=tan(π/4-α)
求证(1-2sinαcosα)/(cos²α-sin²α)=tan(π/4-α)
已知sin(x+π/6)=1/3,求sin(5π/6-x)+sin^2(π/3-x)
sinπ(x-1)=-sinπx如何证明
1-2sin²π/12
2sin^2(π/8)-1,
y=sin(π/4+x/2)sin(π/4-x/2) =sin(π/4+x/2)sin[π/2-(π/4+x/2)]
已知 cos π/5 =(根号5 +1)/4 求 sin π/5,sin -π/5 ,sin 4π/5 ,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