On a plate in the shape of an equilateral triangle \(ABC\) with area \(16\sqrt{3}\) sq cm, a rod \(GD\), of height 8 cm, is fixed vertically at the centre of the triangle. \(G\) is a point on the plate. If the areas of the triangles \(AGD\) and \(BGD\) are both equal to \(4\sqrt{19}\) sq cm, find the area of the triangle \(CGD\) (in sq cm).