Similar to ド・グアの定理

Cavalieri's principle

Carnot's theorem (conics)

Carnot's theorem (inradius, circumradius)

Kiepert conics

Conway circle theorem

Conway triangle notation

Sicherman dice

Schiffler point

Simson line

Spieker circle

Szilassi polyhedron

Stewart's theorem

Soddy circles of a triangle

Soddy line

Ceva's theorem

Cevian

Catalogue of Triangle Cubics

Circumgon

Encyclopedia of Triangle Centers

Astroid

Annulus (mathematics)

Affine space

Circles of Apollonius

Inscribed sphere

Circumcircle

Kepler triangle