f(x)=sin(πx/4-π/6)-2cos²πx/8+1 =sin(πx/4-π/6)-（2cos²πx/8-1） =sinπx/4cosπ/6-cosπx/4sinπ/6-cosπx/4 =√3/2*sinπx/4-3/2cosπx/4 =√3(1/2sinπx/4-√3/2*cosπx/4) =√3sin(πx/4-π/3) T=2π/(π/4)=8
