Catalogue of Triangle Cubics

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The Catalogue of Triangle Cubics is an online resource containing detailed information about more than 1200 cubic curves in the plane of a reference triangle.[1] The resource is maintained by Bernard Gilbert. Each cubic in the resource is assigned a unique identification number of the form "Knnn" where "nnn" denotes three digits. The identification number of the first entry in the catalogue is "K001" which is the Neuberg cubic of the reference triangle ABC. The catalogue provides, among other things, the following information about each of the cubics listed:

  • Barycentric equation of the curve
  • A list of triangle centers which lie on the curve
  • Special points on the curve which are not triangle centers
  • Geometric properties of the curve
  • Locus properties of the curve
  • Other special properties of the curve
  • Other curves related to the cubic curve
  • Plenty of neat and tidy figures illustrating the various properties
  • References to literature on the curve

The equations of some of the cubics listed in the Catalogue are so incredibly complicated that the maintainer of the website has refrained from putting up the equation in the webpage of the cubic; instead, a link to a file giving the equation in an unformatted text form is provided. For example, the equation of the cubic K1200 is given as a text file.[2]

First few triangle cubics in the catalogue[]

The following are the first ten cubics given in the Catalogue.

Identification number Name(s) Equation in barycentric coordinates
K001 Neuberg cubic, 21-point cubic, 37-point cubic
K002 Thomson cubic, 17-point cubic
K003 McCay cubic, Griffiths cubic
K004 Darboux cubic
K005 Napoleon cubic, Feuerbach cubic
K006 Orthocubic
K007 Lucas cubic
K008 Droussent cubic
K009 Lemoine cubic
K010 Simson cubic
First six cubics in the Catalogue of Triangle Cubics

GeoGebra tool to draw triangle cubics[]

Tucker cubic (cubic K011 in the Catalogue) of triangle ABC drawn using the GeoGebra command Cubic(A,B,C,11).

GeoGebra, the software package for interactive geometry, algebra, statistics and calculus application has a built-in tool for drawing the cubics listed in the Catalogue.[3] The command

  • Cubic( <Point>, <Point>, <Point>, n)

prints the n-th cubic in the Catalogue for the triangle whose vertices are the three points listed. For example, to print the Thomson cubic of the triangle whose vertices are A, B, C the following command may be issued:

  • Cubic(A, B, C, 2)

See also[]

References[]

  1. ^ Bernard Gilbert. "Catalogue of Triangle Cubics". Cubics in the Triangle Plane. Bernard Gilbert. Retrieved 27 November 2021.
  2. ^ "K1200: a crunodal KHO-cubic". Cubics in the Trangle Plane. Bernard Gilbert. Retrieved 27 November 2021.
  3. ^ "Cubic Command". GeoGebra. GeoGebra. Retrieved 27 November 2021.
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