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:

“The lifelong process of caregiving, is the ultimate link between caregivers of all ages. You and I are not just in a phase we will outgrow. This is life—birth, death, and everything in between.... The care continuum is the cycle of life turning full *circle* in each of our lives. And what we learn when we spoon-feed our babies will echo in our ears as we feed our parents. The point is not to be done. The point is to be ready to do again.”

—Paula C. Lowe (20th century)

“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)

“There is all the difference in the world between departure from recognised rules by one who has learned to obey them, and neglect of them through want of training or want of skill or want of understanding. Before you can be eccentric you must know where the *circle* is.”

—Ellen Terry (1847–1928)