a)
[tex]v = \frac{ \frac{ {16}^{2} \sqrt{3} }{4} \times 12 }{3} = \frac{256 \sqrt{3} }{4} \times 4 = 64 \sqrt{3} \times 4 = \boxed{256 \sqrt{3} {cm}^{3} }[/tex]
b)
[tex]v = \frac{16 \times 16 \times 12}{3} = 256 \times 4 = \boxed{1024 {cm}^{3} }[/tex]
