sinx+cosx=m(m的绝对值扫码下载作业帮拍照答疑一拍即得
问题描述:
sinx+cosx=m(m的绝对值
扫码下载作业帮
拍照答疑一拍即得
答
sin^3x+cos^3x=(sinx+cosx)(sin^2-sinxcos+cos^2)=(sinx+cosx)(1-sinxcosx)=m(1-(m^2-1)/2)=3m/2-m^3/2
sin^4x+cos^4x=(sin^2x+cos^2x)^2-2sin^2xcos^2x=1-2sin^2xcos^2x=1-2[(m^2-1)/2]^2=1-(m^2-1)/2