The points (3a, 0), (0, 3b) and (a, 2b) are
Vertices of an equilateral triangle
Vertices of an isosceles triangle
Vertices of a right angled isosceles triangle
Hence the points are collinear.
Show that the points (a, 0), (0, b) and (3a, -2b) are collinear. Also find the equation of the line containing them.