9.1 Polygons[2G3]
We present some simple geometrical properties of polygons, that may be rigorously proven either by analytical methods (embedding geometrical objects as subsets of the Cartesian plane), or purely geometrical methods (in the spirit of [ 13 ] ).
In the following we will use the celebrated Jordan Theorem; a simple proof may be found in [ 29 ] .
Theorem
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The proof of the Jordan Theorem usually starts with a simple Lemma (again, see [ 29 ] ; or Theorem 6 [ 13 ] ).
Definition
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Lemma
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Definition
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Remark
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