One of the bisectors of the angle between the lines a(x−1)2+24(x−1)(y−2)+b(y−2)2=0 is x+2y−5=0   then the other bisector

Bisectors are perpendicular to each other, slope of perpendicular bisector is 2It is passing through (1,2)Equation of other bisector is y−2=2(x−1) i.e., 2x−y=0