If the straight line ax+by+c=0make a triangle of constant area with coordinate axes, then

Line ax+by+c=0 meets the coordinate axes at A(-c/a, 0) and (0, -c/b)∴  Area of ΔOAB=12×OA×OB⇒  Area of ΔOAB=12×−ca−cb=c2Clearly, this will be constant, if a, c, b arc in G.P.