求证:cos3xcosx+sin^22x=sin3xsinx+cos^22x
求证(cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2
求证:cos²x+cos²(x+a)-2cosxcosacos(x+a)=sin³a
求证 cos^8(x)-sin^8(x)=cos2x【1-1/2sin^2(2x)】
求证 sinˇ4X+sin²Xcos²X+cos²X = 1
三角等式求证:cos^6x+sin^6x=1-3sin^2x+3sin^4x
sin(sin(sin(sin(x)=cos(cos(cos(cos(x),X等于多少?
求证:cos平方x+cos平方(x+a)-2cosa*cosx*cos(x+a)=sin平方a
求证sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y=1
求证:sin(π/4+x)/sin(π/4-x)+cos(π/4+x)/(π/4-x)=2/cos2x
求证 cos*xcos*y + sin*xsin*y + sin*xcos*y + xin*ycos*x = 1
求证 tan(2π-X)sin(-2π-X)cos(6π-X)/ sin(X+3π/2)*cos(X+3π/2)=-ta
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]