=(cosA+sinA)(cosA-sinA)sin(π/4+A)/2cos(π/4-A)cos(π/4+A)
=[cos2A√2/2(sinA+cosA)]/[2*√2/2(cosA+sinA)*√2/2(cosA-sinA)]
=√2/2cos2A(sinA+cosA)/cos2A
=√2/2(sinA+cosA)