Definitions For Conchoid

Noun

CONCHOID (plural CONCHOIDs) (mathematics, geometry) Any of a family of curves defined as the locus of points p, such that each p is on a line that passes through a given fixed point P and intersects a given curve, C, and the distance from p to the point of intersection with C is a specified constant (note that for nontrivial cases two such points p satisfy the criteria, and the resultant curve has two parts). : The conchoid of a circle with respect to a point on the circle is a cardioid if the fixed distance is equal to the diameter of the circle. : The Conchoid of Nicomedes is the conchoid of a straight line with respect to a point not on the line. (geology) A conchoidal fracture in rock.

Usage notes

The fixed point (P) of the construction may be referred to as the focus of the conchoid; it may also be defined as the origin (of a cartesian coordinate system) or the pole (if polar coordinates are used), and potentially referred to accordingly. The curve C is an example of a directrix.

Derived terms

conchoid of de Sluze {{qualifier, strictly a cissoid}} conchoid of Dürer {{qualifier, not actually a conchoid}} conchoid of Nicomedes

Related terms

conchoidal

Translations

Czech: konchoida, f Russian: конхо́ида, f

Etymology

from {{etyl + la + en}} concha + + mussel (from (ancient greek) κόγχη) + mussel shell or anything in this form./">oid or directly from (ancient greek) κογχοειδής, referring to the curved outline of a mussel shell or anything in this form.