Review the concept of eccentricity through examining the effects of changing
the value of the variable e in the following equation.
We first recall that eccentricity is the fixed ratio of the distance from any point on the
conic to the focus versus the distance from that point to the directrix.
Simply speaking, the eccentricity of a conic is the measure of its curvature.
We can also use eccentricity to determine if a conic will be a circle, ellipse, parabola, or hyperbola.
The general rule is that if e < 1, the conic is an ellipse
if e = 1, the conic is a parabola.
if e > 1, the conic is a hyperbola.
As an addition, we note that if e = 0, the conic is a circle.