f(x)
=cos(2x-π/3)+2sin(x-π/4)sin(x+π/4)
=(1/2)cos2x+ (√ 3/2)sin2x +( cos(π/2) -cos2x )
=-(1/2)cos2x +(√ 3/2)sin2x
= sin(2x-π/6)