The urns $$A$$, $$B$$ and $$C$$ contains 4 red, 6 black; 5 red, 5 black and $$\lambda$$ red, 4 black balls respectively. One of the urns is selected at random and a ball is drawn. If the ball drawn is red and the probability that it is drawn from urn $$C$$ is 0.4, then the square of length of the side of largest equilateral triangle, inscribed in the parabola $$y^2 = \lambda x$$ with one vertex at vertex of parabola is