sin(1/x)-cos(1/x)/x在这个式子中x趋于0+和0-时,两者值相等吗?为什么》

cos x/sin x+sin x/(1+cos x) 化简. 化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 2cos x (sin x -cos x)+1 1/(sin x+cos x) 的不定积分 (1+cos x-sin x)/(1-sin x-cos x)+(1-cos x-sin x)/(1-sin x+cos x)=? cos x/( 1-sin x)化简 (x^2cos^2x-sin^2x)/x^2cos^2xsin^2x （x->0）lim (x^2cos^2x-sin^2x)/x^2cos^2xsin^2x （x->0）=lim [cos^2x-(sin^2x/x^2)]/cos^2xsin^2x=lim (cos^2x-1)/sin^2x=lim -sin^2x/sin^2x=-1这样解错在哪啊?小弟感激不尽 怎么证明2(1-sin x)(1+cos x)=(1-sin x+cos x)^2 化简 1-sin^4x-cos^4x/1-sin^6x-cos^6x 化简(1-cos^4x-sin^4x)/(1-cos^6x-sin^6x) 求值：(1-sin^6 x-cos^6 x)/(1-sin^4 x-cos^4 x) y=(sin(x)-1)/(cos(x)+(cos(x))/(sin(x)+1)的奇偶性 化简：(1+sin x-cos x)/(1+sin x+cos x) 谢 化简 1/2cos x-根号3/2sin x 根3sin x+cos x (SIN X*COS X)/(1+SIN X+COS X)的值域? 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x 求证：tan x/2=sin x/(1+cos x)