Topics in circle geometry

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Tangent circles

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Problem of Apollonius
Apollonian gasket
Steiner chain
Pappus chain, arbelos
Tangent circles
Malfatti circles
Seven circles theorem
Descartes theorem
Coxeter's loxodromic sequence of tangent circles

Inversion

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Circle inversion
Peaucellier linkage
Inscribed angle theorem
Secant-tangent theorem
Power of a point
Radical axis
Radical center
Pole and polar
Coaxal circles, pencil
Monge's theorem
Homothetic center

Rolling circles

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Cycloid
Hypocycloid, astroid, deltoid
Epicycloid, cardioid, nephroid
Spirograph
Hypotrochoid
Epitrochoid
Deferent and epicycle

Circle packing

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Circle packing, Circle tesselation
Tammes problem, Thomson problem
Circle packing theorem

Incircles/excircles of triangles

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Feuerbach's theorem
Equal incircles theorem
incircle, excircle
Japanese theorem

Intersecting circles

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Clifford's circle theorems
Five circles theorem
Six circles theorem
Johnson's theorem
Lune
Miquel's theorem
Pivot theorem
Poncelet's porism

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