斜角的正弦值2分之根号2,倾斜角α=45°,
∴tanα=1,
∴(3-7m+2m^2)/(9-m^2)=1,且m≠±3,
3-7m+2m^2=9-m^2
3m^2-7m-6=0
(3m+2)(m-3)=0
m=-2/3或m=3,
∴m=-2/3.