# Circle

A circle is a simple shape of Euclidean geometry that is the set of all points in the plane that are equidistant from a given point, the centre. The distance between any of the points and the centre is called the radius.

A circle is a simple closed curve which divides the plane into two regions: an interior and an exterior. In everyday use, the term "circle" may be used interchangeably to refer to either the boundary of the figure, or to the whole figure including its interior; in strict technical usage, the circle is the former and the latter is called a disk.

A circle can be defined as the curve traced out by a point that moves so that its distance from a given point is constant.

A circle may also be defined as a special ellipse in which the two foci are coincident and the eccentricity is 0. Circles are conic sections attained when a right circular cone is intersected by a plane perpendicular to the axis of the cone.

### Other articles related to "circle, circles":

Osculating Circle
... differential geometry of curves, the osculating circle of a sufficiently smooth plane curve at a given point p on the curve has been traditionally ... This circle, which is the one among all tangent circles at the given point that approaches the curve most tightly, was named circulus osculans (Latin for "kissing circle") by Leibniz ... The center and radius of the osculating circle at a given point are called center of curvature and radius of curvature of the curve at that point ...
Descartes' Theorem - Definition of Curvature
... Descartes' theorem is most easily stated in terms of the circles' curvatures ... The curvature (or bend) of a circle is defined as k = ±1/r, where r is its radius ... The larger a circle, the smaller is the magnitude of its curvature, and vice versa ...
Lucius Cary, 2nd Viscount Falkland - Great Tew Circle
... For more details on this topic, see Great Tew Circle ... At Great Tew he enjoyed a short but happy period of study, and he assembled a cultured circle, whom the near neighbourhood of the university and his own brilliant qualities attracted to his house ...
Wolfram & Hart - Operations - Circle of The Black Thorn
... The members of the circle act as the earthly instruments of the Senior Partners, charged with being the driving force behind Wolfram Hart's apocalyptic ... The members of the Circle do this not from a belief in evil per se, but because being a Black Thorn allows them to amass power for themselves and wield that power with impunity ... The Circle's lineup in 2004 is Archduke Sebassis Senator Helen Brucker Cyvus Vail Ed, Grand Potentate of the Fell Brethren the leader of the Sahrvin Clan ...
Circle, Montana - Demographics
... There were 291 households out of which 27.8% had children under the age of 18 living with them, 56.0% were married couples living together, 5.5% had a female householder with no husband present, and 36.1% were non-families. 34.4% of all households were made up of individuals and 19.6% had someone living alone who was 65 years of age or older ...

### Famous quotes containing the word circle:

Everything here below beneath the sun is subject to continual change; and perhaps there is nothing which can be called more inconstant than opinion, which turns round in an everlasting circle like the wheel of fortune. He who reaps praise today is overwhelmed with biting censure tomorrow; today we trample under foot the man who tomorrow will be raised far above us.