三角形

$ \triangle ABC

三角 (記号)

BAMBI (geometry)

Congruence (geometry)

Desargues' theorem

Dragon's Eye (symbol)

Fermat point

Hadwiger–Finsler inequality

Heronian triangle

Inertia tensor of triangle

Integer triangle

Law of cosines

Law of sines

Law of tangents

Lester's theorem

List of triangle topics

Ono's inequality

Pedal triangle

Pedoe's inequality

Pythagorean theorem

Special right triangles

Triangle center

Triangular number

Triangulated category

Triangulation (topology)

Apollonius' theorem