圆锥截面
圆锥形截面
二次曲线

[ noun ]
(geometry) a curve generated by the intersection of a plane and a circular cone
<noun.shape>

Conic \Con"ic\, Conical \Con"ic*al\, a. [Gr. ?: cf. F. conique.
See {Cone}.]
1. Having the form of, or resembling, a geometrical cone;
round and tapering to a point, or gradually lessening in
circumference; as, a conic or conical figure; a conical
vessel.

2. Of or pertaining to a cone; as, conic sections.

{Conic section} (Geom.), a curved line formed by the
intersection of the surface of a right cone and a plane.
The conic sections are the parabola, ellipse, and
hyperbola. The right lines and the circle which result
from certain positions of the plane are sometimes, though
not generally included.

{Conic sections}, that branch of geometry which treats of the
parabola, ellipse, and hyperbola.

{Conical pendulum}. See {Pendulum}.

{Conical projection}, a method of delineating the surface of
a sphere upon a plane surface as if projected upon the
surface of a cone; -- much used by makers of maps in
Europe.

{Conical surface} (Geom.), a surface described by a right
line moving along any curve and always passing through a
fixed point that is not in the plane of that curve.