原式=√2/2*[sin(π/4-x)*1/2+cos(π/4-x)*√3/2]
=√2/2*[sin(π/4-x)cosπ/3+cos(π/4-x)sinπ/3]
=√2/2*sin(π/4-x+π/3)
=√2/2*sin(7π/12-x)
=√2/2*sin(π/2+π/12-x)
=√2/2*cos(π/12-x)
=√2/2*cos(x-π/12)