1/sin(x-120)-1/sin(x+120)=4根号3/3,求cosx

(sin 1/x) /x sin(sinx)/x,x 趋于0的极限sin(sin(x))/x=[sin(sin(x))/sin(x)]*sin(x)/x=1*1=1sin(sin(x))/sin(x)这一部我不明白阿 cos x/sin x+sin x/(1+cos x) 化简. x*（1+sin^2 x )/sin^2x 不定积分 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 x+cos x-1)(sin x-cos x+1)/sin 2x (1-(sin^4x-sin^2xcos^2x+cos^4x)/sin^2x +3sin^2x 化简[1-(sin^4 x-sin^2 xcos^2 x+cos^4 x)]/(sin^2 x)+3sin^2 x 化简(sin^2 x/sin x-cosx)-(sin x+cosx/tan^2 x-1) sin(1/X)求导sin（1/X）怎么求导, 求不定积分【sin(x)^5 + sin(x)^3】^(1/2) sin根号下（x+1）-sin根号下x 不定积分sin(x)/(1+e^sin(x)),如何换元 ∫sin²x(1-sin²x)dx是多少? 1-2sinx*sin(60+x)sin(60-x) ∫sin^2x/(1+sin^2x )dx求解, sinπ(x-1)=-sinπx如何证明 证明sin派(x-1)=-sin派x