原式=根号2sin(πx/8+π/4)+根号2sin(π/2 + πx/8+ π/4)
=根号2sin(πx/8+π/4)+根号2cos(πx/8+ π/4)
=2*[根号2/2 *sin(πx/8+π/4)+ 根号2/2 *cos(πx/8+ π/4)]
=2sin(πx/8+π/4 +π/4)
=2sin(πx/8 + π/2)
=2cos(πx/8)