即|4x-3y+1|/√(16+9)=|12x+5y+13|/√(144+25)
13|4x-3y+1|=5|12x+5y+13|
13(4x-3y+1)=5(12x+5y+13)或13(4x-3y+1)=-5(12x+5y+13)
2x+16y+13=0,56x-7y+39=0