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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

## Elements of Euclid [selections from book 1-6] adapted to modern methods in ...

Euclides - 1874 - 234 pages
...tne lines. 8. When one straight line stands on another, so as to make the two adjacent angles equal, each of them is called a right angle; and the straight line standing on the other is said to be perpendicular or at right angles to it. Sj if the line OB, standing...

## Mensuration for elementary and middle class schools

Henry Lewis (M.A.) - Measurement - 1875 - 104 pages
...angle," but it is, perhaps, a little too difficult for beginners: — 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. An acute angle is less than a right angle, as ABD, DEE. An obtuse...

## Primer of geometry

...Wherefore if two straight lines &c. QED RIGHT ANGLES. DEFINITION. When one straight line, standing on another straight line, makes the adjacent angles equal...called a right angle ; and the straight line which stands upon the other is - said to be perpendicular to it. EUCLID'S AXIOM. — All right angles are...

## Modern geometry [ed.] with an appendix by W.B. Jack

Richard Wormell - 1876
...common vertex, and are on opposite sides of a common side. 1 8. When one 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 said to be...

## A Military Dictionary: Comprising Terms, Scientific and Otherwise, Connected ...

George Elliot Voyle, G. de Saint-Clair-Stevenson - English language - 1876 - 676 pages
...applied to substantive rank (viile Rank) in the army. Perpendicular — When a straight line standing on another straight line makes the adjacent angles equal to one another, each of these angles is a right angle, and the line perpendicular. Persian Wheel — A contrivance for raising...

## Euclid's Elements of Geometry: Chiefly from the Text of Dr. Simson, with ...

Robert Potts - Geometry - 1876 - 446 pages
...which is contained by DB. CB, is called the angle DBC, or CUD. X. 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...

## Elements of geometry, based on Euclid, books i-iii

Edward Atkins - 1876 - 119 pages
...equal to the angle EOF (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 callccl a. right angle (Def. 10) ; AD = Make CE = CD nnj A DBF equilatcral. * EC*' ....

## Elements of geometry, based on Euclid, book i

Edward Atkins - 1877
...may be expressed by the letter at that point, as the angle K 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...