[Math Lair] Elements: Book II, Definitions

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The following is as given in Sir Thomas L. Heath's translation, which can be found in the book The Thirteen Books of The Elements, Vol. 1.

Elements on the Math Lair
Book IBook IIBook IX
Definitions, Postulates, and Common NotionsDefinitionsProposition 20
Proposition 1, Proposition 3, Proposition 14Proposition 36
Proposition 5, Proposition 6,  
Proposition 29, Proposition 47  


  1. Any rectangular parallelogram is said to be contained the the two straight lines containing the right angle.
  2. And in any parallelogrammic area let any one whatever of the parallelograms about its diameter with the two complements be called a gnomon.