Let's write the standard form of a horizontal hyperbola equation:
[tex]\frac{(x-h)^2}{a^2}-\frac{(y-k)^2}{b^2}=1[/tex]Where the center is located at (h, k), the vertices are located at (h±a, k), the foci are located at (h±c, k) and the asymptotes are:
[tex]y=\pm\frac{b}{a}(x-h)+k[/tex]Comparing the standard form with the equation x^2/4 - y^2/16 = 1, we have:
h = 0, k = 0, a = 2 and b = 4.
The value of c was already calculated: c = 2√5.
Therefore the vertices are (-2, 0) and (2, 0), the foci are (-2√5, 0) and (2√5, 0) and the asymptotes are:
[tex]y=\pm2x[/tex]