欧几里得几何的五条公理 —

**从一点向另一点可以引一条直线。

**任何线段都能向两边无限延伸成一条直线。

**任何给定的线段，均可以其一个端点为圆心，以该线段作为半径做一个圆。

**所有直角都相等。

**通过直线以外的一个点，存在且仅存在一条与该直线平行的直线。

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Euclidean geometry’s 5 self-evident axioms:

1. A straight line may be drawn between any two points.
2. Any terminated straight line may be extended indefinitely.
3. A circle may be drawn with any given point as center and any given radius.
4. All right angles are equal.

5. For any given point not on a given line, there is exactly one line through the point that does not meet the given line.

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