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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 and Conic Sections - Page 10
by Elias Loomis - 1857 - 226 pages

## The elements of plane geometry, from the Sansk. text of Ayra Bhatta, ed. by ...

Āryabhaṭa - 1878
...subjoined B is an angle and is thus expressed : " Angle AB 0." A BC XVI. When a straight line standing on another straight line makes the adjacent angles equal to one another, each of these angles is called a right angle ; and the straight line which stands on the other is called a...

## Explanatory Mensuration

Alfred Hiley - 1879 - 230 pages
...sides AB, AC, but upon the extent or opening between the lines. XI. When a straight line standing upon another straight line makes the adjacent angles equal to one another, each of them is called a right A angle ; and the straight line standing upon the other is called a perpendicular to it. Thus if AB,...

## Moffatt's pupil teachers' course (ed. by T. Page). Candidates, 2nd (-4th) year

Moffatt and Paige - 1879
...may be expressed by one letter at that point, as the angle at E. 10. 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...

## The Elements of Plane and Solid Geometry: With Chapters on Mensuration and ...

Isaac Sharpless - Geometry - 1879 - 282 pages
...When a straight line standing on another straight line makes the adjacent angles equal to each other, each of them is called a right angle, and the straight line which stands on the other is called a perpendicular. 9. An obtuse 1 angle is one that is greater than a right...

## Euclid, books i. & ii., with notes, examples, and explanations, by a late ...

Euclides - 1879
...which the lines meet is often called the vertex of the angle.] 10. When a straight line standing on another straight line makes the adjacent angles equal to one another, each of these angles is called a right angle ; and the straight line which stands on the other is called a...

## The Elements of Euclid for the Use of Schools and Colleges: With Notes, an ...

Isaac Todhunter - Euclid's Elements - 1880 - 400 pages
...equal to the angle CHG ; [I. 8. and they are adjacent angles. But 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...

## First principles of Euclid: an introduction to the study of the first book ...

T S. Taylor - 1880 - 152 pages
...B.) A D DEFINITION OF RIGHT ANGLES. JTigr.J. Euc. Def. io.) — 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 -A. -0 .*...

## Practical Geometry for Second Grade Art-pupils and Private Schools

Thomas Newton Andrews - Geometry - 1881 - 160 pages
...falls upon the straight line AB, and makes ftigfif flight the angles on either side of it A/tgle Anq-/e equal to one another, each of ^ them is called a right angle, and the line CD is said to be perpendicular to the line A B. a Fig. 1. K Drawing Board 5_ ^ B I We read the...