已知cosa(π/6-α)=根号3/3 ,求sin(π/2+α)

cosa(π/6-α)=√3/3
sina(π/6-α)=±√6/3
当sina(π/6-α)=√6/3时
sin(π/2+α)
=sin[2π/3-(π/6-α)]
=sin(2π/3)cos(π/6-α)-cos(2π/3)sin(π/6-α)
=√3/2*√3/3-(-1/2)*√6/3
=1/2+√6/6
当sina(π/6-α)=-√6/3时
sin(π/2+α)
=sin[2π/3-(π/6-α)]
=sin(2π/3)cos(π/6-α)-cos(2π/3)sin(π/6-α)
=√3/2*√3/3-(-1/2)*（-√6/3)
=1/2-√6/6

cosa(π/6-α)=√3/3
sina(π/6-α)=±√6/3
当sina(π/6-α)=√6/3时
sin(π/2+α)
=sin[2π/3-(π/6-α)]
=sin(2π/3)cos(π/6-α)-cos(2π/3)sin(π/6-α)
=√3/2*√3/3-(-1/2)*√6/3
=1/2+√6/6

已知 cosa(π/6-α)=√3 / 3求sin(π/2+α) 方法1：cos(α - β) = cosαcosβ + sinα sinβcosa(π/6-α) = cosπ/6*cosα + sinπ/6* sinα =√3 / 2*cosα + 1/2* sinα = √3 / 3所以：√3 / 2*cosα + 1/2* √...