证明:(sinx)^2+sin(x+60度)^2+sin(x+120度)^2=3/2
证明sin(x+y)sin(x-y)=(sinx)^2-(siny)^2.
证明成立:[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x).
证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+
sin(x+y)-sinx=2cos(x+1/2y)sin(1/2y)的详细证明步骤.
利用cosx=sin(π/2-x),sin'x=cosx,证明(cosx)'=-sinx
证明等式:[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x).成立
证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx
2sinx=sin(60-x),求sinx的值
证明tanx-sinx/sin^3(x)=1-cosx/cosxsin^2(x)
怎样证明sinx^2,sin(x绝对值),cos(根号x)不是周期函数
已知函数f(x)=2cosx*sin(x+π/3)-√3sin^2x+sinx*cosx
设f(x)=2cosx.sin(x+π/3)-根号3 sin平方x+sinx.cosx