quae erant demonstranda

A form of quod erat demonstrandum — which was to be proved; which was to be demonstrated.

OriginLatin quae erant dēmonstranda →
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Meanings

phrase
  1. pluralplural of quod erat demonstrandum

    Therefore it is established that the join CD will be equal, or less, or greater than this AB, according as the angles at the same CD are right, or obtuse, or acute. Quae erant demonstranda.

    1894, Benjamin Franklin Finkel, The American mathematical monthly: devoted to the interests of collegiate mathematics, volume 1, Mathematical Association of America, page 190
    1 more example

    The proving of a geometrical theorem is, of course, an exercise in logical thinking, but the pupil needs to be made conscious of this, and also conscious of the fact that the same processes of thought are applicable in quite other fields and will lead to equally satisfactory results (quae erant demonstranda) there too.

    1955, Maurice Leonard Jacks, The education of good men, Gollancz, page 47

Origin

  1. Latinquae erant dēmonstranda“which were to be proved”
  2. Englishquae erant demonstranda

Unadapted borrowing from Latin quae erant dēmonstranda (“which were to be proved”).

More words from Latin

Full word history & related roots →
Cite this entry
APA

quae erant demonstranda. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/quae%20erant%20demonstranda

MLA

“quae erant demonstranda.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/quae%20erant%20demonstranda. Accessed November 5, 2026.

Chicago

WatkinsX Dictionary, s.v. “quae erant demonstranda,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/quae%20erant%20demonstranda.

Source: quae erant demonstranda on Wiktionary, CC BY-SA 4.0.