化简:(1)sin(兀/4-x)sin(兀/4+x)(2)cosA+COS(120度-A)+cos(120度+A)(3)(sin2x/1+cos2x)(cosx/1+cosx)zxtc:(2)是PASS了(1)再详细一点(3)没看懂

化简[1-(sin^4 x-sin^2 xcos^2 x+cos^4 x)]/(sin^2 x)+3sin^2 x 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x cos x/sin x+sin x/(1+cos x) 化简. 傅里叶级数作图f（x）=2sin[x] - sin[2x] + 2/3sin[3x] - 1/2sin[4x]我用mathematica输入程序Plot[{2sin[x],-2sin[x],2sin[x] - sin[2x],-2sin[x] + sin[2x],2sin[x] - sin[2x] + 2/3sin[3x],-2sin[x] + sin[2x] - 2/3sin[3x],2sin[x] - sin[2x] + 2/3si 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x 化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 化简 1-sin^4x-cos^4x/1-sin^6x-cos^6x 化简(1-cos^4x-sin^4x)/(1-cos^6x-sin^6x) (1-(sin^4x-sin^2xcos^2x+cos^4x)/sin^2x +3sin^2x 化简(sin^2 x/sin x-cosx)-(sin x+cosx/tan^2 x-1) 化简2sin^2[(π/4)+x]+根号3（sin^x-cos^x）-1 (sin 1/x) /x 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] s = 2*sin(x)-sin(2*x)+2/3*sin(3*x)-1/2*sin(4*x)+2/5*sin(5*x)用matlab画图,求教啊 化简sin(-2x) 化简sin²x 化简cos^4x+sin^4x