# Definition:Ellipse/Minor Axis

< Definition:Ellipse(Redirected from Definition:Minor Axis of Ellipse)

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## Definition

Consider an ellipse $K$ whose foci are $F_1$ and $F_2$.

### Definition $1$

The **minor axis** of $K$ is the line segment through the center of $K$ perpendicular to the major axis of $K$ such that its endpoints are the points of intersection with $K$.

### Definition $2$

The **minor axis** of $K$ is the diameter of $K$ which has the smallest length.

In the above diagram, $C_1 C_2$ is the **minor axis** of $K$.

### Semi-Minor Axis

A **semi-minor axis** of $K$ is either half of the minor axis of $K$ from its midpoint to its endpoint.

## Also see

- Equivalence of Definitions of Minor Axis of Ellipse
- Minor Axis of Ellipse is Axis of Symmetry
- Definition:Major Axis of Ellipse

- Results about
**the minor axis of an ellipse**can be found**here**.

## Linguistic Note

The plural of **axis** is **axes**, which is pronounced **ax-eez** not **ax-iz**.

Compare basis.