directrix

English

Wikipedia

Noun

In this picture of an ellipse, a parabola, and an hyperbola, the black line is their shared directrix.

directrix (plural directrices)

1. A female who directs; a directress.
2. (geometry) A line used to define a curve or surface; especially a line, the distance from which a point on a conic has a constant ratio to that from the focus

Derived terms

• conic section directrix
• graph directrix
• ruled surface directrix

Translations

a line used to define a curve or surface

Polish: kierownica (pl) f.