An oval with two axes of symmetry constructed from four arcs (top), and comparison of blue oval and red ellipse with the same dimensions of short and long axes (bottom).
This oval, with only one axis of symmetry, resembles a chicken egg.
In
technical drawing an
oval (from Latin
ovum, 'egg') is a figure constructed from two pairs of arcs, with two different
radii (see image on the right). The arcs are joined at a point, in which lines
tangential to both joining arcs lie on the same line, thus making the joint smooth. Any point of an oval belongs to an arc with a constant radius (shorter or longer), whereas in an
ellipse the radius is continuously changing.
Oval in geometry
In
geometry, an
oval or
ovoid is any
curve resembling an
egg or an ellipse, but not 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:
- their shape does not depart much from that of an ellipse, and
The word ovoidal refers to the characteristic of being an ovoid.
An ovoid is the surface generated by rotating an oval curve about one of its axes of symmetry.
Other examples of ovals described elsewhere include:
Egg shape
The shape of an
egg is approximately that of half each a
prolate (long) and roughly spherical (potentially even slightly
oblate/short)
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 2-dimensional figure that, revolved around its
major axis, produces the 3-dimensional surface.
Projective planes
In the theory of
projective planes,
oval is used to mean a set of
q + 1 points in PG(2,q) with no 3 on any line, the projective plane over the
finite field with
q elements. See
oval (projective plane).
In common English
In common speech 'oval' means a shape rather like an egg or an ellipse, and it may be two-dimensional or three-dimensional.
See also
Category:Curvesde:Oval (Geometrie)es:Óvaloeu:Obalo (geometria)fr:Ovaleio:Ovaloit:Ovaleka:ოვალიlt:Ovalasnl:Ovaalja:オーバルno:Ovalpl:Owalpt:Ovalru:Овалsimple:Ovalsl:Oval (geometrija)sr:Овалtl:Habilogwar:Pilidong
