Move the sliders for [math] a[/math] and [math]c[/math] to see what they do to the conic. When [math]a<c[/math], we have a hyperbola. When [math]a>c[/math], we have an ellipse. What happens when[math] c=0[/math]? Here, [math]V1[/math] and [math]V2[/math] are vertices, [math]F1[/math] and[math] F2[/math] are foci, and [math]e[/math] is the eccentricity.