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Proposition: Prop. 9.18: Condition for Existence of Third Number Proportional to Two Numbers

Euclid's Formulation

For two given numbers, to investigate whether it is possible to find a third (number) proportional to them.

• Let $A$ and $B$ be the two given numbers.
• And let it be required to investigate whether it is possible to find a third (number) proportional to them.

Modern Formulation

(not yet contributed)

Table of Contents

Proofs: 1

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References

Adapted from (subject to copyright, with kind permission)

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

Adapted from CC BY-SA 3.0 Sources:

1. Prime.mover and others: "Pr∞fWiki", https://proofwiki.org/wiki/Main_Page, 2016