Thus projective geometry deals with triangles, quadrangles, and so on, but not with right-angled triangles, paralleograms, and so on.
-Projective Geometry, Coxeter pg 3.
The first question of the section is:
Which of the following figures belongto projective geometry:
The book states that both choices (ii) an isosceles triangle and (iii) a triangle and its medians, are not in projective geometry.
A bit confused about why exactly. Is it beccause projective geometry has no unit of measurement?