In hyperbolas, the vertices and foci always lie on the same axis. We let [math]a[/math] denote the distance from the origin to a vertex.

[i]This applet was developed for use with [url=https://www.pearson.com/en-us/subject-catalog/p/interactive-calculus-early-transcendentals-single-variable/P200000009666]Interactive Calculus[/url], published by Pearson.[/i][br]