Paris et New York sont-ils les coins d’un carré ? - Liceo Scientifico R. Bruni (Padova)

We had to figure out whether Paris and New York could be the verticies of a square, approximating the Earth as a sphere, we thus had to understand spherical geometry from the fundamentals, like how can we measure angles, and if we can define a square in the same way we define it in Euclidean geometry.