2(sina)^2-sinacosa-3(cosa)^2
=(2sina-3cosa)(sina+cosa)=0
∵00
∴sina+cosa>0
∴2sina-3cosa=0
tana=3/2,
sina=3/√13,cosa=2/√13
sin(a+π/4)/(sin2a+cos2a+1)
=√2/2(sina+cosa)/(2sinacosa+2(cosa)^2)
=√2/(4cosa)
=√26/8