Chapter 9 - Section 9.2 - The Hyperbola - Exercise Set - Page 981: 2

Graph (d)

Vertices: $(1,0)$ and $(-1,0)$ $ c^2=a^2+b^2=4+1=5$ $ c= \sqrt 5= 2.23$ Foci: $(2.23,0); (-2.23,0)$ This matches graphs (b) and (d). We choose graph (d) because the value under $y^2$ is larger than the value under $x^2$. Thus, it is graph (d).