pons asinorum

[ as-uh-nawr-uhm, -nohr- ]

noun

, Geometry.

1. a geometric proposition that if a triangle has two of its sides equal, the angles opposite these sides are also equal: so named from the difficulty experienced by beginners in mastering it. Euclid, 1:5.

pons asinorum

/ ˌæsɪˈnɔːrəm /

noun

1. the geometric proposition that the angles opposite the two equal sides of an isosceles triangle are equal

Word History and Origins

Origin of pons asinorum¹

First recorded in 1745–55; from Latin pōns asinōrum “bridge of asses”

Word History and Origins

Origin of pons asinorum¹

Latin: bridge of asses, referring originally to the fifth proposition of the first book of Euclid, which was considered difficult for students to learn

Example Sentences

I asked, with a scornful laugh; 'why, that's a mere pons asinorum!

From Project Gutenberg

By means of his third and fourth propositions he is now able to prove the pons asinorum, that the angles at the base of an isosceles triangle are equal.

From Project Gutenberg

Roger Bacon speaks of Euclid's fifth proposition as "elefuga," and it also gets the name of "pons asinorum" from its point of transition to higher learning.

From Project Gutenberg

The bridge of stability is therefore not even a pons asinorum.

From Project Gutenberg

But we will not now traverse the ethical pons asinorum of necessity—the most simple and evident of mortal truths, and the most darkened, tortured, and belabored by moral teachers.

From Project Gutenberg