Ellipses
Categories: coordinate systems pure mathematics
An ellipse is a stretched circle.
The longest diameter, $PQ$, is called the major axis. The shortest diameter, $RS$, is called the minor axis. The major and minor axes are always perpendicular.
An ellipse can be defined by the parameters $a$ and $b$, where the major axis has length $2a$ and the minor axis has length $2b$ (or vice versa). An ellipse centred on the origin with its major and minor axes aligned with the x and y axes looks like this:
The ellipse crosses the x axis at points (a, 0) and (-a, 0). It crosses the y axis at points (0, b) and (0, -b).
A circle is a special case of an ellipse, where the major and minor axes have the same length.
Related articles
Join the GraphicMaths Newsletter
Want article discussions, announcements, and discounts on GraphicMaths books and products? Join the newsletter:
