Question

f two lines intersect, then they intersect at exactly one point. theorme or postulate

Answer 1

A postulate is a statement that is assumed true without proof.
A theorem is a true statement that can be proven.

Can you prove that, when two lines intersect, they only intersect at one point?

Answer 2

Truth is, you might have two lines that intersect at infinitely many points, if they are coincident. Two distinct lines intersect at most once. It has been a long time since I taught geometry, but I think this can be proven by contradiction. It might depend on which theorems you have available to work with.