Inversion transforms circles into circles; if it passes through the center of inversion, the image circle becomes a straight line

Inscribed Angle in Circle

Simson Line

Circle Power

Radical Axis

Radical Axis - Pencil of Circles

Radical Center

Circle Inversion

Circle Inversion - Circles and Lines

Circle Polar Line

Circle Polar Line Reciprocity

Exterior Point

Interior Point

Exterior Point - Bitangent Circle

Interior Point - Bitangent Circle

D'Alembert Theorem

Apollonius Tangency Problem

Apollonius Tangency Problem

Apollonius Tangency Problem - 8 circles

Miquel's Theorem

Clifford's Theorem

Five Circles Theorem

Ptolemy's Theorem

Ptolemy's Theorem with an Equilateral Triangle

Equal Incircles Theorem

Three Tangents Theorem

Apollonius Circle

Constant Chord Theorem

Malfatti Circles

Feuerbach's Circle

Deltoid

Deltoid in an Astroid

Nested Hypocycloids

Complementary Hypocycloids

Inversion transforms circles into circles; if it passes through the center of inversion, the image circle becomes a straight line