函数y=cosx(sinx-根号3cosx)+ 根号3 /2当x=-π/2,x=0时,函数值为多少

问题描述:

函数y=cosx(sinx-根号3cosx)+ 根号3 /2
当x=-π/2,x=0时,函数值为多少

y=cosx(sinx-根号3cosx)+ 根号3 /2
=sinxcosx-根号3(cosx)^2+根号3 /2
=sin2x/2-根号3*(cos2x+1)/2+根号3 /2
=sin2x*1/2-cos2x*根号3 /2
=sin(2x-π/3)
再将x=-π/2,x=0分别代入就可以求出值了!

y=cosx(sinx-√3cosx)+√3/2
=cosxsinx-√3(cosx)^2+√3/2
=sin2x/2-√3cos2x/2
=sin(2x-π/3)
当x=-π/2时y=sin(-π-π/3)=sinπ/3=√3/2
当x=0时y=sin(-π/3)=-√3/2