sinx+cosx-2=根号2sin(x+派/4)-2是怎么来的?

求证sinx-cosx=根号2sin(x-π/4) 为什么cosX+sinX=...为什么cosx+sinx=根号2 sin(x+π/4) sinx+cosx=根号2sin(?) 求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx 证明:sin2x=2sinx*cosx为什么sin(x+x)=sinx*cosx+cosx*sinx? sinx+cosx/sinx-cosx=2 求sinx/cos^3x +cosx/sin^3x 求证sin^2x/sinx-cosx-(sinx+cosx)/(tan^2-1)=sinx+cosx谢谢GGJJ 若sinx+cosx=根号2,那么sin^4x+cos^4x的值是多少? 若sinx+cosx=根号2,那么sin^4x+cos^4x的值 若sinX+cosX=根号2,求sin^3X+cos^3X的值 f(x)=[2sin(x+π/3)+sinx]cosx-根号3sin2x,化简 (sin^x/sinx-cosx)-sinx+cosx/tan^2x-1 利用cosx=sin(π/2-x),sin'x=cosx,证明(cosx)'=-sinx 3sinx-2cosx=0 (1)(cosx-sinx)/(cosx+sinx)+(cosx+sinx)/(cosx-sinx) (2)sin^2 x-2sinxcosx+4cos^2 x f(x)=2sin^2-2根号3*sinX*cosX+1的周期怎么求如题, sinx+cosx-2=根号2sin(x+派/4)-2是怎么来的? 若(cos2x)/[sin(x-π/4)]=（-根号2）/2,则cosx+sinx=? cos2x/sin{x-π/4}=-根号2/2求cosx+sinx的值