3.2.13 Lines on a plane

condition: Given two lines on the plane: \( m: 3 x-4 y+1=0 \) and \( l: x-4 y=0 \). Find: a) equations of lines separated from the line \( m \) at a distance equal to three; b) the angle between the lines \( m \) and \( l \); c) the length of the vector starting from the origin and ending at the point of intersection of the lines \( m \) and \( l \).