cos[π/2-(π/3+x)]=cos(π/6-x)=sin(π/3+x)y=sin(x+π/3)cos(π/6-x) =sin(x+π/3)sin(π/3+x) =sin²(π/3+x) =[1-cos(2π/3+2x)]/2 =1/2-1/2cos(2π/3+2x)T=2π/2=π
