Petersen-Morley theorem

proper noun

A theorem stating that, if a, b, c are three general skew lines in space, if a′, b′, c′ are the lines of shortest distance respectively for the pairs (b,c), (c,a) and (a,b), and if p, q and r are the lines of shortest distance respectively for the pairs (a,a′), (b,b′) and (c,c′), then there is a single line meeting at right angles all of p, q, and r.

Meanings

proper nounthe Petersen-Morley theorem
  1. geometryA theorem stating that, if a, b, c are three general skew lines in space, if a′, b′, c′ are the lines of shortest distance respectively for the pairs (b,c), (c,a) and (a,b), and if p, q and r are the lines of shortest distance respectively for the pairs (a,a′), (b,b′) and (c,c′), then there is a single line meeting at right angles all of p, q, and r.

Origin

Named after Johannes Trolle Petersen (later Johannes Hjelmslev) and Frank Morley.

Full word history & related roots →
Cite this entry
APA

Petersen-Morley theorem. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/Petersen-Morley%20theorem

MLA

“Petersen-Morley theorem.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Petersen-Morley%20theorem. Accessed November 5, 2026.

Chicago

WatkinsX Dictionary, s.v. “Petersen-Morley theorem,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/Petersen-Morley%20theorem.

Source: Petersen-Morley theorem on Wiktionary, CC BY-SA 4.0.