- Conic section - Plane curve - A curve formed by a section of a cone, when the cutting
plane makes a greater angle with the base than the side of the cone
makes. It is a plane curve such that the difference of the distances
from any point of it to two fixed points, called foci, is equal to a
given distance. See Focus. If the cutting plane be produced so as to
cut the opposite cone, another curve will be formed, which is also an
hyperbola. Both curves are regarded as branches of the same hyperbola.
See Illust. of Conic section, and Focus.
- Anything that has a form resembling that of a cone. - A solid formed by the revolution of a conic section about
its axis; as, a parabolic conoid, elliptic conoid, etc.; -- more
commonly called paraboloid, ellipsoid, etc. - A surface which may be generated by a straight line moving
in such a manner as always to meet a given straight line and a given
curve, and continue parallel to a given plane. - Resembling a cone; conoidal.
- The line drawn through a focus of a conic section
parallel to the directrix and terminated both ways by the curve. It is
the parameter of the principal axis. See Focus, and Parameter.
- A directress. - A line along which a point in another line moves, or
which in any way governs the motion of the point and determines the
position of the curve generated by it; the line along which the
generatrix moves in generating a surface. - A straight line so situated with respect to a conic
section that the distance of any point of the curve from it has a
constant ratio to the distance of the same point from the focus.
- A straight line on a circle passing through the centre point - Distance across a circle - I am kept in to deter thickness, in circle - Straight line through a circle - Thickness - Transverse measurement - Twice radius
- Centre - Clear definition - Concentrate - Concentrate attention on - Concentrate like a photographer? - Concentrate on listening to people swear - Obsessed with detail