# What Is the Definition of Directrix?

Directrix refers to a fixed line that is used in describing a curve or surface. This term is mostly used in mathematics and it can also be defined as a fixed curve traversed by a generatrix in generating a conic section, a cylinder or a median line in the trajectory of fire of an artillery piece.
di·rec·trix
[dih-rek-triks, dahy-]
NOUN [PLURAL DI·REC·TRIX·ES, DI·REC·TRI·CES]
1.
Geometry a fixed line used in the description of a curve or surface.
2.
Archaic. a directress.
Source: Dictionary.com
Q&A Related to "What Is the Definition of Directrix"
 (x-h)² = 4p(y-k) This is the standard form when the parabola has a vertical axis. The vertex of this parabola is at (h, k). The focus is at (h, k + p). The directrix is the line http://answers.yahoo.com/question/index?qid=200802...
 All of the first answer is correct but I don't think really addresses your question. You draw a line (the directrix) anywhere. You specify a point (the focus) not on that line. You http://answers.yahoo.com.au/question/index?qid=200...
 The answer to your question is what the first answerer says: that a focus point and a directrix defines a parabola. However, in middle school and high school mathematics, we never http://answers.yahoo.com/question/index?qid=200812...
 A parabola is defined as the locus of a point which moves in a plane in such a way that jt is always equidistant from a given fixed point called the focus and a given fixed line called http://answers.yahoo.com/question/index?qid=200701...
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'Directrices' is the plural form of the word directrix, which refers to a fixed line that is used in describing a curve or surface. This term is commonly used ...