What was A postulate that was developed and accepted by greek mathematicians?

Answer 1

The Pythagorean Theorum.

Answer 2

One postulate developed and accepted by Greek mathematicians was the Parallel Postulate, which stated that given a line and a point not on that line, there is exactly one line through the point that is parallel to the given line. This postulate was crucial in the development of Euclidean geometry. However, it was later discovered that this postulate is not actually necessary for generating consistent geometries, leading to the development of non-Euclidean geometries.