Final answer:
The answer explains why there must be at least two lines on any given plane by referencing mathematical theorems and providing examples.
Explanation:
Theorem 1:
Two straight lines of a plane have either one point or no point in common. For example, two intersecting lines on a piece of paper.
Theorem 2:
Through a straight line and a point not on it, one and only one plane can be created. Imagine a line on a piece of paper with a point above it forming a unique plane.
Theorem 5:
Every straight line in a plane divides the remaining points into two regions. This is evident when a line separates a drawing into two distinct areas.
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