List of circle topics
This list of circle topics includes things related to the geometric shape, either abstractly, as in idealizations studied by geometers, or concretely in physical space. It does not include metaphors like "inner circle" or "circular reasoning" in which the word does not refer literally to the geometric shape.
Geometry and other areas of mathematics
; Circle anatomy- Annulus
- Area of a disk
- Bipolar coordinates
- Central angle
- Circular sector
- Circular segment
- Circumference
- Concentric
- Concyclic
- Degree
- Diameter
- Disk
- Horn angle
- Measurement of a Circle
- Pi
- * List of topics related to pi
- Pole and polar
- Power of a point
- Radical axis
- Radius
- * Radius of convergence
- * Radius of curvature
- Sphere
- Tangent lines to circles
- Versor
- Apollonian circles
- Circles of Apollonius
- Archimedean circle
- Archimedes' circles – the twin circles doubtfully attributed to Archimedes
- Archimedes' quadruplets
- Circle of antisimilitude
- Bankoff circle
- Brocard circle
- Carlyle circle
- Circumscribed circle
- Coaxal circles
- Director circle
- Fermat–Apollonius circle
- Ford circle
- Fuhrmann circle
- Generalised circle
- GEOS circle
- Great circle
- * Great-circle distance
- * Circle of a sphere
- Horocycle
- Incircle and excircles of a triangle
- Inscribed circle
- Johnson circles
- Magic circle
- Malfatti circles
- Nine-point circle
- Orthocentroidal circle
- Osculating circle
- Riemannian circle
- Schinzel circle
- Schoch circles
- Spieker circle
- Tangent circles
- Twin circles
- Unit circle
- Van Lamoen circle
- Villarceau circles
- Woo circles
- Apollonian gasket
- Arbelos
- Bicentric polygon
- Bicentric quadrilateral
- Coxeter's loxodromic sequence of tangent circles
- Cyclic quadrilateral
- Cycloid
- Ex-tangential quadrilateral
- Hawaiian earring
- Inscribed angle
- Inscribed angle theorem
- Inversive distance
- Inversive geometry
- Irrational rotation
- Lens
- Lune
- * Lune of Hippocrates
- Lazy caterer's sequence
- Overlapping circles grid
- Pappus chain
- Polar circle
- Power center
- Salinon
- Semicircle
- Squircle
- Steiner chain
- Tangential polygon
- Tangential quadrilateral
- Apollonius' problem
- * Limiting cases of Apollonius' problem
- Belt problem
- Benz plane
- Bertrand's paradox
- Bonnesen's inequality
- Brahmagupta's formula
- Buffon's needle problem
- Bundle theorem
- Butterfly theorem
- Carnot's theorem
- Casey's theorem
- Circle graph
- Circle map
- Circle packing
- * Circle packing in a circle
- * Circle packing in an equilateral triangle
- * Circle packing in an isosceles right triangle
- * Circle packing theorem
- * Introduction to Circle Packing – a book by Kenneth Stephenson
- Circular surface
- Clifford's circle theorems
- Compass and straightedge
- * Mohr–Mascheroni theorem
- * Poncelet–Steiner theorem
- Descartes' theorem
- Dinostratus' theorem
- Dividing a circle into areas
- Equal incircles theorem
- Five circles theorem
- Gauss circle problem
- Gershgorin circle theorem
- Geometrography
- Hadamard three-circle theorem
- Hardy–Littlewood circle method
- Isoperimetric problem
- Japanese theorem for cyclic polygons
- Japanese theorem for cyclic quadrilaterals
- Kosnita's theorem
- Lester's theorem
- Milne-Thomson circle theorem
- Miquel's theorem
- Monge's theorem
- Mrs. Miniver's problem
- Pivot theorem
- Pizza theorem
- Squaring the circle
- Poncelet's porism
- Ptolemy's theorem
- Ptolemy's table of chords
- Regiomontanus' angle maximization problem
- Ring lemma
- Seven circles theorem
- Six circles theorem
- Smallest circle problem
- Tammes problem
- Tarski's circle-squaring problem
- Thales' theorem
- Circle criterion
- Circle group
- * Group of rational points on the unit circle
- Circular algebraic curve
- Circular distribution
- Circular statistics
- Mean of circular quantities
- Polygon-circle graph
- Splitting circle method
- von Mises distribution
- Wigner semicircle distribution
- Wrapped distribution
- * Wrapped Cauchy distribution
- * Wrapped normal distribution
- Thomas Baxter
Physical sciences and engineering
- Centrifugal force
- Centripetal force
- Circle of confusion
- Circle of forces
- Circular dichroism
- Circular orbit
- Mohr's circle
- Non-uniform circular motion
- Thomson problem
- Uniform circular motion
Geography
- Arctic Circle
- Antarctic Circle
- Circle of latitude
- Equator
- Great-circle distance
- Polar circle
- Position circle
- Tropic of Cancer
- Tropic of Capricorn
Artifacts
- Addendum circle
- Belt problem
- Center pivot irrigation
- Circular ditches
- Circular slide rule
- Compass
- Crop circle
- Dip circle
- List of gear nomenclature
- Peaucellier-Lipkin linkage
- Pitch circle
- Repeating circle
- Timber circle
- Traffic circle
- * List of circles in Washington, D.C.
- * List of traffic circles in New Jersey
- Setting circles
- Stone circle
- Wheel
Glyphs and symbols
- Borromean rings
- Circled dot
- Circles in Polish mythology
- Crescent
- Dotted circle
- Enso
- Magic circle
- Olympic emblem
- Ouroboros
- Petosiris to Nechepso
- Quatrefoil
- Ring
- Roundel
- Sacred Chao
- Shield of the Trinity
- Solar symbols
- Squared-circle postmark
- Sun cross
- Symbol of Tanit
- Trefoil
- Triquetra
- Vesica piscis
- Triple Goddess symbol
- Yin and yang