If the two pairs of lines 2x2+6xy+y2=0 and 4x2+18xy+by2=0 are equally inclined, then b=

Both the pairs have same pair of angular bisectorsequation of angular bisector is3(x2-y2)=(2-1)xy.............1equation of angular bisector of second equation 9(x2-y2)=(4-1)xyboth equations represent same