Books Books When a straight line standing on another straight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the straight line which stands on the other is called a perpendicular to it. Elements of Geometry and Conic Sections - Page 10
by Elias Loomis - 1857 - 226 pages ## Classics in the History of Greek Mathematics

Jean Christianidis - Mathematics - 2004 - 502 pages
...BA is perpendicular to AT and Definition I.10, which states that “When a straight line set up on a straight line makes the adjacent angles equal to one another, each of the right angles is right, and the straight line standing on the other is called a perpendicular to... ## Visualization, Explanation and Reasoning Styles in Mathematics

Paolo Mancosu, Klaus Frovin Jørgensen, S.A. Pedersen, Stig Andur Pedersen - Mathematics - 2005 - 336 pages
...classes of (rectilinear) angles (trans. Heath 1926, I, 181): 1 0. When a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right [...]. 1 1 . An obtuse angle is an angle greater than a right angle. 12.... ## The Thirteen Books of Euclid's Elements

Euclid - 452 pages
...EB ; therefore the angle AFE is equal to the angle BFE. [i. 8] But, when a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right ; [i. Def. 10] 20 therefore each of the angles AFE, BFE is right. Therefore... ## Euclid in Greek, Volume 1

Euclid - Euclid's Elements - 1920 - 304 pages
...straight line on which it stands.' The full translation then is: 'When a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right, and the straight line standing on the other is called a perpendicular to... ## The Thirteen Books of Euclib's Elements.

Euclid - 454 pages
...is equal to the angle EHC. [1.8] And they are adjacent angles. But, when a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right, and the straight line standing on the other is 30 called a perpendicular... 