directrix
noun
a fixed line used in the description of a curve or surface.
directrices
-
pluralof directrix.plural
The grammatical form denoting more than one person, place, thing, or idea.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Figure 1.54 The three conic sections with their foci and directrices.
From Textbooks ● Mar. 30, 2016
Figure 7.54 The three conic sections with their foci and directrices.
From Textbooks ● Mar. 30, 2016
The surface may be considered as generated by an ellipse moving parallel to itself along two ellipses as directrices.
From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various
The ellipse and the hyperbola have two foci and two directrices.
From An Elementary Course in Synthetic Projective Geometry by Derrick Norman Lehmer
In the hyperbola on the other hand d1 − d2 is constant, equal to the distance between the directrices, therefore in this case r1 − r2 is constant.
From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various
