Circle

Definition

A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. The distance between any point of the circle and the centre is called the radius. The length of a line segment connecting two points on the circle and passing through the centre is called the diameter. A circle bounds a region of the plane called a disc.

Related concepts

Abstract art Affine sphere Algebraic number Ambient isotopy Angle Angle bisector theorem Annulus (mathematics)Anti-clockwise Apeirogon Apollonian circles Apollonius of Perga Approximations of π Arabic Arc length Archimedean circle Archimedes Archimedes' twin circles Area Area (geometry)Area of a circle Area of a disk Arthur Koestler Astrology and astronomy Astronomical Astronomy Bankoff circle Bi (jade)Bicentric polygon Brocard circle C. Stanley Ogilvy Calculus Carlyle circle Cartesian coordinate system Cartesian oval Cassini oval Cave painting Central angle Centre (geometry)Chebyshev distance Chord (geometry)Chromatic circle Circle (disambiguation)Circle fitting Circle group Circle of antisimilitude Circles of Apollonius Circular arc Circular points at infinity Circular sector Circular segment Circumcircle Circumference Circumscribe Circus Classical antiquity Clockwise College Mathematics Journal Collinear Compass-and-straightedge construction Compass (drafting)Compass (drawing tool)Compass and straightedge Complete angle Complex plane Complex projective plane Concentric Conic section Connected space Convex polygon Coordinate system Creation myth Cross-ratio Curve of constant width Cut-the-Knot Cyclic polygon Cyclic quadrilateral Degeneracy (mathematics)Degree (angle)Dharmachakra Diameter Director circle Directrix circle Disk (mathematics)Distance Eight-point circle Ellipse Encyclopedia of Mathematics Encyclopædia Britannica Eleventh Edition Equation Equilateral triangle Eric W. Weisstein Euclid Euclid's Elements Euclidean metric European Mathematical Society Excircle Exterior angle Ferdinand von Lindemann Ford circle Full moon Gauss circle problem Gear Generalised circle Geodesic circle Geometers Geometry Graph of a function Great circle Greek language Halo (religious iconography)History of science in the Middle Ages Homeomorphism Homeric Greek Homogeneous coordinates Hypersphere Hypocycloid Implicit differentiation Incircle Incircle and excircles of a triangle Inscribed angle Inscribed angle theorem Inscribed circle Interior angle Intersecting chords theorem Inversion in a circle Irrational number Isoperimetric inequality Johnson circles Lemoine circle Length Lens (geometry)Lester circle Limiting case (mathematics)Lindemann–Weierstrass theorem Line (geometry)Line segment Line–circle intersection List of circle topics List of planar symmetry groups Locus (mathematics)Lp space Magic circle Malfatti circles Mandart circle MathWorld Mathematical constant Measurement of a Circle Metathesis (linguistics)Midpoint Nebra sky disc Nine-point circle One-dimensional Orientation (vector space)Orthocentroidal circle Orthogonal group P-norm Parametric equation Parametric variable Parry circle Perimeter Perpendicular Perpendicular bisector Petroglyph Pi Plane (mathematics)PlanetMath Plato Point (geometry)Polar circle (geometry)Polar coordinates Polynomial Power of a point Proclus Proportionality (mathematics)Pseudomath Pythagorean theorem Radian Radius Rational number Real coordinate space Reflection symmetry Regular pentagon Regular polygon Rhind papyrus Riemannian circle Right angle Root of a function Rotational symmetry Sagitta (geometry)Santa Barbara County, California Schoch circles Science Secant line Semicircle Seventh Letter Shape Signed angle Similarity (geometry)Sine-triple-angle circle Sphere Spieker circle Square Squaring the circle Stereographic projection Stone circle Subtend Superellipse Supplementary angles Symmetry group Tangent Tangent half-angle substitution Tangent line Tangent lines to circles Tangential polygon Tangential quadrilateral Tau (mathematical constant)Taxicab geometry Thales' theorem The Sleepwalkers (Koestler book)Three points determine a circle Timber circle Topology Transcendental number Translation of axes Triangle Trigonometric function Turn (angle)Unit circle Unit sphere Van Lamoen circle Versine Vertex (geometry)Victor J. Katz Villarceau circles Von Neumann neighborhood Wassily Kandinsky Weighted sum Western esotericism Wheel Wikimedia Commons Wikisource Woo circles

5 concepts already in your glossary