Definition:Hyperbola/Directrix
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Definition
Let $K$ be a hyperbola specified in terms of:
- a given straight line $D$
- a given point $F$
- a given constant $\epsilon$ such that $\epsilon > 1$
where $K$ is the locus of points $P$ such that the distance $p$ from $P$ to $D$ and the distance $q$ from $P$ to $F$ are related by the condition:
- $q = \epsilon \, p$
The line $D$ is known as a directrix of the hyperbola.
Sources
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): hyperbola
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): hyperbola
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): hyperbola