Oval (geometry)
In geometry, an oval or ovoid is any curve resembling an egg or an
ellipse. Unlike other curves, the term 'oval' is not well-defined and many distinct curves are commonly called ovals. These curves have in common that:
* they are differentiable , simple ,
convex, closed, plane curves;
* their
shape does not depart too much from that of a
circle or an
ellipse, and
* there is at least one
axis of symmetry.
The word ovoidal refers to the characteristic of being ovoid.
Two examples of ovals are shown below.
Encyclopedia
In geometry, an
oval or
ovoid is any curve resembling an egg or an
ellipse. Unlike other curves, the term 'oval' is not well-defined and many distinct curves are commonly called ovals. These curves have in common that:
The word ovoidal refers to the characteristic of being ovoid.
Two examples of ovals are shown below. In , a
semicircle is joined to half an ellipse while in , two semicircles are connected with straight line segments.
Other
ad hoc constructions are often encountered as well.
This second oval shape is called a "rounded rectangle", not really an oval, but racing tracks and sports fields of all sorts are called ovals while being rounded rectangles.
Other examples of ovals described elsewhere include:
Egg shape
The shape of an egg is approximately that of half each a
prolate and roughly spherical
ellipsoid joined at the equator, sharing a principal axis of
rotational symmetry, as illustrated above. Although the term
egg-shaped usually implies a lack of
reflection symmetry across the equatorial plane, it may also refer to true prolate ellipsoids. It can also be used to describe the 2D figure that, revolved around its
major axis, produces the 3D surface.
Projective planes
In the theory of
projective planes,
oval is used to mean a set of
q + 1 non-
collinear points in PG, the projective plane over the finite field with
q elements. See oval .
