If the equation $$3x^2-kxy-3y^2=0$$ represents the bisectors of angles between the lines $$x^2-3xy-4y^2=0$$, then value of k is

The joint equation of pair of lines through the origin and making an equilateral triangle with the line $$y=3$$ is

If the acute angle between the lines given by $$\mathrm{a x^2+2 h x y+b y^2=0}$$ is $$\frac{\pi}{4}$$, then $$\mathrm{4 h^2=}$$

The joint equation of the pair of lines through the origin and making an equilateral triangle with the line $$x=3$$ is