English

Perimeter Variance of Uniform Random Triangles

Probability 2010-07-05 v1 Combinatorics Metric Geometry

Abstract

Let T be a random triangle in a disk D of radius R (meaning that vertices are independent and uniform in D). We determine the bivariate density for two arbitrary sides a,b of T. In particular, we compute that E(a*b)=(0.837...)*R^2, which implies that Var(perimeter)=(0.649...)*R^2. No closed-form expression for either coefficient is known. The Catalan numbers also arise here.

Keywords

Cite

@article{arxiv.1007.0261,
  title  = {Perimeter Variance of Uniform Random Triangles},
  author = {Steven Finch},
  journal= {arXiv preprint arXiv:1007.0261},
  year   = {2010}
}

Comments

9 pages

R2 v1 2026-06-21T15:43:40.249Z