it's the point-line postulate, you can use it as part of a set of axioms equivalent to Euclid but it definitely not one of Euclid's https://en.wikipedia.org/wi

it's the point-line postulate, you can use it as part of a set of axioms equivalent to Euclid but it definitely not one of Euclid's https://en.wikipedia.org/wiki/Point%E2%80%93line%E2%80%93plane_postulate https://en.wikipedia.org/wiki/Point%E2%80%93line%E2%80%93pla...