pons asinorum

American  

[as-uh-nawr-uhm, -nohr-] / ˌæs əˈnɔr əm, -ˈnoʊr- /

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 British  

/ ˌæsɪˈnɔːrəm /

noun

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

---

Etymology

Origin of pons asinorum

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

Example Sentences

The pons asinorum is free to all comers and even the eternal triangle's points are true for either hemisphere.

From Time Magazine Archive

A month or two ago you blundered on "pons asinorum."

From Time Magazine Archive

This proposition has long been called the pons asinorum, or bridge of asses, but no one knows where or when the name arose.

From The Teaching of Geometry by Smith, David Eugene

That a picture must have a subject is the first pons asinorum to be crossed, the child usually preferring to remain on the farther side.

From Pictorial Composition and the Critical Judgment of Pictures by Poore, Henry Rankin

I soon saw that the young girl who had been chosen as the star pupil to wrestle with the pons asinorum was giving an exhibition of memorizing and not of mathematical reasoning.

From Mobilizing Woman-Power by Blatch, Harriot Stanton