若x=兀/12 sin^4-cos^4=

为了方便我化一下：x=兀/12=15度,另外偶不晓得√是不是表示根号.sin^4-cos^4=(sin^2+cos^2)(sin^2-cos^2)=1*(sinx+cosx)(sinx-cosx)=√2sin(x+45)sin(x-45)=2sin60*sin(-30)=-√3/2p.s.孩子,你发错地方了,这里是小说...