In geometry, the locus of a point moving
according to specified conditions. The circle
is the locus of all points equidistant from a
given point (the centre). Other common
geometrical curves are the ellipse, parabola,
and hyperbola, which are also produced when a
cone is cut by a plane at different angles.
Many curves have been invented for the
solution of special problems in geometry and
mechanics - for example, the cissoid (the
inverse of a parabola) and the cycloid.