Find P by letting y = 0 in the tangent equation, P(2a, 0)
Find Q by letting x = 0 in the normal equation, Q(0, -\frac{2a\sqrt{3}}{3})
Find the equation of PQ.
Sub it in the equation of ellipse.
Discriminant = 0 (or factorise it in to a perfect square) therefore touches it.
Unsure if it's...