求证 cos^8(x)-sin^8(x)=cos2x【1-1/2sin^2(2x)】
求证 cos^8(x)-sin^8(x)=cos2x【1-1/2sin^2(2x)】
求证:cosx+cos2x+...+cosnx={[cos(n+1)x/2]*[sin(n/2)x]}/[sin(x/2
求证:sin(π/4+x)/sin(π/4-x)+cos(π/4+x)/(π/4-x)=2/cos2x
求证(cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2
f(x)=(1+cos2x)/[4sin(pai/2+x)]-asin(x/2)cos(pai-x/
求证 sinx(cos^2 2x-sin^2 2x) + 2cosx cos2x sin2x= sin 5x
三角等式求证:cos^6x+sin^6x=1-3sin^2x+3sin^4x
已知sin(x/2)+cos(x/2)=1/2,则cos2x=?
化简:2cos2x+2sin^2 x+cos(-x)分之sin2x+sin(π-x)=___________
求证sin^2x+sin^2y-sin^2x*sin^2y+cos^2x*cos^2y=1
[sin^2(x)-cos^2(x)] 为什么等于-cos2x
已知函数f(x)=1+cos2x/4sin(pai/2-x)-asinx/2cos(7pai-x/2)