A straight line may be drawn from any point to any other point.
A finite straight line may be extended continuously in a straight line.
A circle may be described with any centre and any radius.
All right angles are equal to each other.
If a straight line meets two other straight lines so as to make the two interior angles on one side of it together less than two right angles, the other straight lines, if extended indefinitely, will meet on that side on which angles are less than two right angles.
KeywordsIdeal Point Euclidean Geometry Double Point Projective Geometry Radial Line
- Coxeter, H.S.M. (1998): Introduction to Geometry, 2nd ed., Wiley, N.Y.Google Scholar
- Flegg, H.G. (1974): From Geometry to Topology, Reprinted 2001, Dover, Mineola, NY.Google Scholar
- Lee, J.M. (1997): Riemannian Manifolds, Springer, N.Y.Google Scholar
- Veblen, O. & J.W. Young (1910): Projective Geometry, Vol.I, 1910; Vol.II (O. Veblen sole author), 1918, Ginn and Co., Boston.Google Scholar