Question

Which of the following is known as a simpler form of Euclid's fifth postulate

and led to the discovery of non-Euclidean geometry?
A. Playfair's axiom
B. Poincaré disk
C. Riemann's negation
D. Zeno's paradox

Answer 1

A. Playfair's axiom.

Explanation:

In a plane, given a line and a point not on it, at most, one line parallel to the given line can be drawn through the point.

- this implies Euclid's fifth postulate.