As necessary as the directrix is to the curve, so are the corresponding laws to the State.
directrix, a fixed line that is required for the description of a curve.
Similarly, in an hyperbola a vertex is nearer 704 to the directrix than to the focus.
If a parabola roll on another parabola, their vertices coinciding, the focus of the first traces out the directrix of the second.
With your permission I will add a few words to those I have already uttered with regard to the directrix.
The surface formed by revolving the catenary about its directrix is named the alysseide.
The only surface of revolution having this property is the catenoid formed by the revolution of a catenary about its directrix.
Since the tension is measured by the height above the directrix these two catenaries have the same directrix.
"You probably forget the important difference between a directrix and an axis," hotly observed Barbican.
If the directrix, focus and eccentricity be given, we may employ the general method for constructing a conic.