Where does the term “asses’ bridge” come from and What does asses’ bridge mean?

Sometimes called pons asinorum, which, perhaps more politely, says exactly the same thing in Latin.

Germans translate the Latin into Esels-briicke; French use pont aux lines, but they all refer to the fifth proposition of the first book of Euclid:

If a triangle has two of its sides equal, the angles opposite these sides are also equal.

The proof of this simple bridge-shaped figure is so difficult for those beginning the study of geometry as to give rise to the name, whatever the native country of the student.