6(sinx)^2=4+cosx怎么化简成6cos2x+cosx-2=0
已知2sin2x-cos2x+sinxcosx-6sinx+3cosx=0,求2cosx(sinx+cosx)1+tan
已知4sinx^2-cosx^2-6sinx+3cosx=0,求(cos2x-cosx^2)/(1-cotx^2)的值
sinX+cosX=1/2,cos2X=?
为什么cos2x=cosx^2-sinx^2
为什么cos2X=(cosX)^2-(sinX)^2
已知sinx=-1/2cosx,cosx-sinx/cosx+sinx+sin2x+cos2x的值
3sinx-2cosx=0 (1)(cosx-sinx)/(cosx+sinx)+(cosx+sinx)/(cosx-s
怎么证明cos2x/1-sin2x = cosx+sinx/cosx-sinx
cos3x+2cosx=0 .sinx tan x/2 =1 .sinx - cosx = san2x -cos2x
已知,函数y=cos2x+(sinx)^2-cosx (即y=cos2x + sinx^2 x- cosx)
求证:(1-2sinx×cosx)/cos2x-sin2x=(cos2x-sin2x)/(1+2sinx×cosx)
sinx+2cosx=0,则sin2x+cos2x=