3 Configurations of 9 Lines with 3 Intersection Points on each Line
Contents
Theorem
There exist exactly $3$ essentially different configurations of $9$ straight lines each of which has exactly $3$ points of intersection.
This is one: there are two others.
Proof
The precise meaning of the term "essentially different" needs to be established, for a start
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Also see
Sources
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $9$
