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Let the straight line EF, which falls upon the two straight lines AB, CD, make the alternate angles AEF, EFD equal to one another; AB is parallel to CD.
Euclid's Elements of Geometry: The First Six, the Eleventh and Twelfth Books - Page 32
by Euclid, Edmund Stone - 1765 - 464 pages

## Mathematics: Mechanic's bids and estimates. Mensuration for beginners. Easy ...

Seymour Eaton - 1899 - 340 pages
...straight lines shall be parallel to one another. Let the straight line EF, which falls on the two straight lines AB, CD, make the alternate angles AEF, EFD equal to one another ; then AB shall be parallel to CD. Construction : For if it be not parallel, AB and CD being produced...

## Introduction and books 1,2

Euclid - Mathematics, Greek - 1908
...lines will be parallel to one another. For let the straight line EF falling on the two straight [' s lines AB, CD make the alternate angles AEF, EFD equal ' to one another ; I say that AB is parallel to CD. For, if not, AB, CD when pro- AE / B ducedwill meet either in the direction...

## A Course in Modern Geometries

Judith Cederberg - Mathematics - 2004 - 441 pages
...straight lines will he parallel to one another. For let the straight line EF falling on two straight lines AB, CD make the alternate angles, AEF, EFD equal to one another; I say that AB is parallel to CD. For, if not, AB, CD when produced will meet either in the direction...

## Science and Religion, 400 B.C. to A.D. 1550: From Aristotle to Copernicus

Edward Grant - Religion - 2004 - 307 pages
...opening words of Proposition 27, which assert: "For let the straight line EF falling on the two straight lines AB, CD make the alternate angles AEF, EFD equal to one another" (see Figure 3.1) (Euclid 1956, 1:307). Figure 3.1. Book 1, Proposition 27 of Euclid's Elements, which...

## The Thirteen Books of Euclib's Elements.

Euclid
...straight lines will be parallel to one another. For let the straight line EF falling on the two straight S lines AB, CD make the alternate angles AEF, EFD equal to one another ; I say that AB is parallel to CD. For, if not, AB, CD when pro- AE/ B duced will meet either in the direction...