Minor axis

Definition

The minor axis of an ellipse is the shortest diameter that passes through the center and is perpendicular to the major axis. It bisects the ellipse into two equal halves along its shortest dimension.

5 Must Know Facts For Your Next Test

1. The length of the minor axis is $2b$, where $b$ is the semi-minor axis.
2. The minor axis is always perpendicular to the major axis.
3. In a standard form equation of an ellipse, $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$, $b$ represents the semi-minor axis when $a > b$.
4. The endpoints of the minor axis are located at $(0, \pm b)$ in a horizontally oriented ellipse centered at the origin.
5. The minor axis helps define the shape and eccentricity of an ellipse.

Review Questions

Related terms

Major Axis:

The longest diameter that passes through the center of an ellipse and bisects it into two equal halves along its longest dimension.

Semi-Major Axis: Half of the major axis; it extends from the center to a vertex on the longest part of an ellipse.

Eccentricity:

A measure of how much an ellipse deviates from being circular, calculated as $e = \sqrt{1 - \frac{b^2}{a^2}}$ for ellipses.