In details

Spatial geometry


Points, lines and planes

In spatial geometry, primitive concepts (and therefore accepted without definition) are the concepts of point, line and plane. We usually use the following notation:

  • points: capital letters of our alphabet

  • straight: lowercase letters of our alphabet


  • plans: lowercase letters of the Greek alphabet

Note: Space is the set of all points.

For example, from the following figure we can write:

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