Category:Directrices
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This category contains results about Directrices.
Definitions specific to this category can be found in Definitions/Directrices.
Directrix of Ruled Surface
A directrix is a curve which defines the generators of a ruled surface.
Directrix of Conic Section
Let $K$ be a conic section specified in terms of:
- a given straight line $D$
- a given point $F$
- a given constant $e$
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:
- $q = e p$
The line $D$ is known as the directrix of the conic section.
Directrix of Conchoid
Let $\KK$ be a conchoid.
Let $\CC$ be the curve with respect to which the conchoid is constructed.
$\CC$ is known as the directrix of $\KK$.
Subcategories
This category has the following 2 subcategories, out of 2 total.
D
- Directrices of Ellipses (1 P)
- Directrices of Ruled Surfaces (empty)