Question

Consider the terms pyramid, line, square, and triangle. The term
is not defined in Euclidean geometry.

Answer 1

unfortunately you just have to know/memorize what the three undefined terms in euclidian geometry are to solve this

https://mathbitsnotebook.com/Geometry/BasicTerms/BTundefined.html#:~:text=There%20are%2C%20however%2C%20three%20words,three%20undefined%20terms%20of%20geometry%22.