sin(50+x)cos(10-x)-cos(130-x)sin(170+x) 快.

sin（sin（sin（sin（x）=cos（cos（cos（cos（x）,X等于多少? sin(1/x)-cos(1/x)/x (x*sin x*cos x)的导数 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 求值：sin(10°+x)cos(50°-x)+sin(50°-x)cos(10°+x) 化简sin(x)(cos(x)+cos(3x)+cos(5x)+cos(7x)) cos 2x /sin^2 x*cos^2 x不定积分 2cos x (sin x -cos x)+1 (sin^2x+cos^2x )(sin^2x-cos^2x)怎么得sin^2x-cos^2x? sin(-x)=sin(x),cos(-x)=-cosx对吗? 化简 cos^2(x)*sin^2(x)-sin^2(x) 化简 cos^(2)(x)*sin^(2)(x)-sin^(2)(x)