x为第二象限角,sinx=根号15/4 cosx= -1/4
sin(x+π/4)/sin2x+cos2x+1=[根号2/2(sinx+cosx)]/[2sinxcosx+2(cosx)^2]
=[根号2/2(sinx+cosx)]/[2cosx(sinx+cosx)]
=根号2/4cosx
=-根号2