Supplementary mathematics/Cone

A cone is a geometric body that is created when all the points of a bounded and connected area lying in one plane are connected in a straight line with a point outside the plane. If the patch is a circular disk, the solid is called a circular cone. The area is called the base area, its boundary line is the directrix, the point is called the tip, apex or vertex of the cone and the area on the side is called the lateral surface. A cone has a vertex (the apex), an edge (the directrix) and two faces (the lateral and the base).

The vertex of a cone is not a vertex because the vertex is not an endpoint of edges (see definition of vertex).

The height of the cone means both the perpendicular from the tip to the base (i.e. the height is always perpendicular to the base) and the length of this perpendicular (i.e. the distance between the tip and the base).

The lines connecting the tip with the directrix are called generatrices, their union forms the cone envelope or the lateral surface. Ellipse, parabola and hyperbola are conic sections. In connection with conic sections, a "cone" is often understood as a "double cone".

Especially in technology, a cone or a truncated cone is often referred to as a cone (from Latin conus) or conical.