Proposition: 1.35: Parallelograms On the Same Base and On the Same Parallels

Euclid's Formulation

Parallelograms which are on the same base and between the same parallels are equal1 to one another. * Let $ABCD$ and $EBCF$ be parallelograms on the same base $BC$, and between the same parallels $AF$ and $BC$. * I say that $ABCD$ is equal to parallelogram $EBCF$.

fig35e

Modern Formulation

Parallelograms on the same base (\(\overline{BC}\)) and between the same parallels (\(\overline{AF}\), \(\overline{BC}\)) are equal in area.

Proofs: 1

Proofs: 1 2 3


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References

Adapted from CC BY-SA 3.0 Sources:

  1. Callahan, Daniel: "Euclid’s 'Elements' Redux" 2014

Adapted from (Public Domain)

  1. Casey, John: "The First Six Books of the Elements of Euclid"

Adapted from (subject to copyright, with kind permission)

  1. Fitzpatrick, Richard: Euclid's "Elements of Geometry"

Footnotes


  1. Here, for the first time, "equal" means "equal in area", rather than "congruent" (translator's note).