Editing Equilateral triangle (section)

=== Applications ===
[[File:Give way outdoor.jpg|thumb|Equilateral triangle usage as a yield sign]]
Equilateral triangles have frequently appeared in man-made constructions and in popular culture. In architecture, an example can be seen in the cross-section of the [[Gateway Arch]] and the surface of the [[Vegreville egg]].{{sfnp|Pelkonen|Albrecht|2006|p=[https://archive.org/details/eerosaarinenshap0000saar/page/160 160]}}{{sfnp|Alsina|Nelsen|2015|p=[https://books.google.com/books?id=2F_0DwAAQBAJ&pg=PA22 22]}} It appears in the [[flag of Nicaragua]] and the [[flag of the Philippines]].{{sfnp|White|Calderón|2008|p=[https://archive.org/details/culturecustomsof00stev/page/3 3]}}{{sfnp|Guillermo|2012|p=[https://books.google.com/books?id=wmgX9M_yETIC&pg=PA161 161]}} It is a shape of a variety of [[traffic sign|road signs]], including the [[yield sign]].{{sfnp|Riley|Cochran|Ballard|1982}}

The equilateral triangle occurs in the study of [[stereochemistry]]. It can be described as the [[molecular geometry]] in which one atom in the center connects three other atoms in a plane, known as the [[trigonal planar molecular geometry]].{{sfnp|Petrucci|Harwood|Herring|2002|p=413–414|loc=See Table 11.1}}

In the [[Thomson problem]], concerning the minimum-energy configuration of <math>n</math> charged particles on a sphere, and for the [[Tammes problem]] of constructing a [[spherical code]] maximizing the smallest distance among the points, the best solution known for <math>n=3</math> places the points at the vertices of an equilateral triangle, [[Circumscribed sphere|inscribed in the sphere]]. This configuration is proven optimal for the Tammes problem, but a rigorous solution to this instance of the Thomson problem is unknown.{{sfnp|Whyte|1952}}