Linked from
The 32 pages that link to Equilateral triangle, each with the reason it gives.
TriangleBroader topic: Equal sides force the most symmetric possible triangle.
OrthocenterBroader topic: Its orthocenter coincides with its centroid, circumcenter, and incenter.
IncircleBroader topic: Its incenter, circumcenter, centroid, and orthocenter coincide, simplifying incircle calculations.
Nine-point circleBroader topic: Its center points coincide, so the nine-point circle is concentric with its circumcircle and has half its radius.
Sierpiński triangleBroader topic: The standard construction begins with this shape and subdivides it into four congruent triangles.
Euler's inequalityBroader topic: It is precisely the triangle for which R = 2r.
Weitzenböck's inequalityBroader topic: Its side lengths attain equality, identifying the sharp case of the bound.
Feuerbach's theoremBroader topic: Its centers coincide in highly symmetric ways, making the tangencies easy to inspect.
Hadwiger–Finsler inequalityBroader topic: It is the equality case, attaining the smallest possible ratio of squared side sum to area.
Pedoe's inequalityBroader topic: Taking both triangles equilateral realizes equality and checks the sharp constant 48.
Star of DavidBroader topic: Two such triangles form the star’s basic geometry.
Fagnano's problemBroader topic: Its orthic triangle is equilateral and centered, making the minimizing configuration especially symmetric.
Barrow's inequalityBroader topic: Its symmetry makes side-distance sums especially simple to evaluate.
Conway circle theoremBroader topic: Its symmetry makes the six tangency points form a regular hexagonal arrangement on the circle.
Droz-Farny line theoremBroader topic: Its central orthocenter provides a highly symmetric test configuration.
Equal Incircles TheoremBroader topic: Its inradius is fixed by its side length, giving a simple comparison case.
Gilbert–Pollak conjectureBroader topic: Its Steiner tree uses a central 120-degree junction and attains the ratio √3/2.
Lester's theoremBroader topic: Its symmetry makes the triangle centers coincide in ways that degenerate the usual Lester-circle configuration.
Marden's theoremBroader topic: For equilateral roots, symmetry places the derivative zeros at the incenter and the ellipse center.