sin(arccos1/4)=?

y=90+arctanx/(x-2) y=0.5*arccos1/根号(4-x^2) y=arcsin(x^2-x+1) y=arccos1/x (x>1) y=根号下1-x,≤1 求 定义域 sin^4+cos^4=1,求sin+cos= 证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+ (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=? sin^2x+cos^2x)(sin^4x-sin^2xcos^2x+cos^4x) =sin^4x-sin^2xcos s = 2*sin(x)-sin(2*x)+2/3*sin(3*x)-1/2*sin(4*x)+2/5*sin(5*x) sin阿尔法+sin贝塔=? 计算：arcsin(-根号2/2)-arccos(-1/2)+arctan(-1)-arccos1 sinα+cosβ=3/4,cosα+sinβ=-5/4,求sin(α-β)的值 已知函数fx=（1+1/tanx）sin^x-2sin（x+π/4)sin（x-π/4） 已知sinα-2cosα=10求(sinα-4cosα)/(5sinα+2cosα)