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.
Read more about Circle: Terminology, History, Properties, Circle of Apollonius, Circles Inscribed in Or Circumscribed About Other Figures, Circle As Limiting Case of Other Figures
Famous quotes containing the word circle:
“... [a] girl one day flared out and told the principal “the only mission opening before a girl in his school was to marry one of those candidates [for the ministry].” He said he didn’t know but it was. And when at last that same girl announced her desire and intention to go to college it was received with about the same incredulity and dismay as if a brass button on one of those candidate’s coats had propounded a new method for squaring the circle or trisecting the arc.”
—Anna Julia Cooper (1859–1964)
“They will mark the stone-battlements
And the circle of them
With a bright stain.
They will cast out the dead
A sight for Priam’s queen to lament
And her frightened daughters.”
—Hilda Doolittle (1886–1961)
“And year by year our memory fades
From all the circle of the hills.”
—Alfred Tennyson (1809–1892)