歐幾裏得幾何的五條公理 —
**從一點向另一點可以引一條直線。
**任何線段都能向兩邊無限延伸成一條直線。
**任何給定的線段，均可以其一個端點為圓心，以該線段作為半徑做一個圓。
**所有直角都相等。
**通過直線以外的一個點，存在且僅存在一條與該直線平行的直線。
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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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