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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, based on Euclid, book i - Page 23
by Edward Atkins - 1877

## The Teaching of Geometry

David Eugene Smith - Geometry - 1911 - 360 pages
...confine our attention to having the concept understood. 10. 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 that...

## Standard American Cyclopedia of Steam Engineering: A Treatise on the Care ...

Calvin Franklin Swingle - Steam engineering - 1913 - 1270 pages
...same straight line as in Fig. 34. Fig. 34. Fig. 35. When a straight line, standing on another straight line, makes the adjacent angles equal to one another,...stands on the other is called a perpendicular to it as in Fig 35. Fig. 36. An obtuse angle is that which is greater than a right angle- as in Fig. 36....

## Stories about Mathematics-land, Volume 2

D. Ponton - Mathematics - 1927 - 168 pages
...made when two straight lines cross one another. When a straight line, standing on another straight line, makes the adjacent angles equal to one another,...stands on the other is called a perpendicular to it. A right angle contains 90 degrees. An Obtuse Angle is one which is greater than a right angle. An Acute...

## Geometry, Relativity, and the Fourth Dimension

Rudy von Bitter Rucker - Science - 1977 - 166 pages
...postulate is not clear until we have defined right angles: "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." This postulate seems to be equivalent to the assumption that the things we...

## The Foundations of Geometry and the Non-Euclidean Plane

G.E. Martin - Mathematics - 1997 - 536 pages
...angle are straight, the angle is called rectilineal. 10. 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 that...

## Geometry and the Visual Arts

Daniel Pedoe - Mathematics - 1983 - 338 pages
...angle are straight, the angle is called rectilineal. 10. 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 that...

## Collected Works of Bernard Lonergan: Collection

Bernard J. F. Lonergan, Robert M. Doran - Philosophy - 1988 - 372 pages
...It is a nominal definition. The tenth definition reads: '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 that...

## Geometry: A Comprehensive Course

Daniel Pedoe - Mathematics - 1988 - 468 pages
...the angle are straight, the angle is called rectilineal. 10 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 that...