1/2 sol: An altitude of an equilateral triangle is therefore \(\sqrt{3}\) times the length of half the side length of the triangle. Therefore, an equilateral triangle with side length 4 has altitude length \(\sqrt{3}(4/2) = 2\sqrt{3}\), and area \((2\sqrt{3})(4)/2 = 4\sqrt{3}\) square units. The shaded regions consist of two of these equilateral triangles, so their total area is \(2(4\sqrt{3}) = \boxed{8\sqrt{3}}\) .