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(1) All rulings are parallel to a plane, the directrix plane. (2) All rulings intersect a fixed line, the axis. The conoid is a right conoid if its axis is perpendicular to its directrix plane. Hence all rulings are perpendicular to the axis. Because of (1) any conoid is a Catalan surface and can be represented parametrically by
A cone can be generated by moving a line (the generatrix) fixed at the future apex of the cone along a closed curve (the directrix); if that directrix is a circle perpendicular to the line connecting its center to the apex, the motion is rotation around a fixed axis and the resulting shape is a circular cone.
The directrix is often taken as a plane curve, in a plane not containing the apex, but this is not a requirement. [1] In general, a conical surface consists of two congruent unbounded halves joined by the apex. Each half is called a nappe, and is the union of all the rays that start at the apex and pass through a point of some fixed space curve ...
Directrix is a spaceship in the Lensman series of novels by E. E. Smith. Directrix is the name of an alternative punk band in Chicago. Directrix - a feminine form of director in the context of grammatical gender
In geometry, a surface S in 3-dimensional Euclidean space is ruled (also called a scroll) if through every point of S, there is a straight line that lies on S. Examples include the plane , the lateral surface of a cylinder or cone , a conical surface with elliptical directrix , the right conoid , the helicoid , and the tangent developable of a ...
Hebrew punctuation – Punctuation conventions of the Hebrew language over time; Glossary of mathematical symbols; Japanese punctuation; Korean punctuation; Ordinal indicator – Character(s) following an ordinal number (used of the style 1st, 2nd, 3rd, 4th or as superscript, 1 st, 2 nd, 3 rd, 4 th or (though not in English) 1º, 2º, 3º, 4º).
The ellipse thus generated has its second focus at the center of the directrix circle, and the ellipse lies entirely within the circle. For the parabola, the center of the directrix moves to the point at infinity (see Projective geometry). The directrix "circle" becomes a curve with zero curvature, indistinguishable from a straight line.
The Diccionario de la lengua española [a] (DLE; [b] English: Dictionary of the Spanish language) is the authoritative dictionary of the Spanish language. [1] It is produced, edited, and published by the Royal Spanish Academy, with the participation of the Association of Academies of the Spanish Language.