Euclidean geometry/Obsolete definitions

Axioms two and five of euclidean geometry are conditional or faulty. Some definitions have been improved by non-euclidean geometry for accuracy.

Axiom five: parallel axiom
Axiom number five is known as the parallel axiom.

It states If a straight line falling on two straight lines makes the interior angles of the same side of it taken together less than two right angles than the two straight lines if produced indefinitely meet on that side on which the sum of the angles is less than two right angles.

Theorem 16
Has been improved upon, for better use.