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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.
Euclid, books i. & ii., with notes, examples, and explanations, by a late ... - Page 1
by Euclides - 1879

The Elements of Euclid: The Errors, by which Theon, Or Others, Have Long Ago ...

Robert Simson - Trigonometry - 1806 - 546 pages
...line standing on another straight lii>e makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the straight...stands on the other is called a perpendicular to it. XI. An obtuse angle is that which is greater than a right angle. XII. An acute angle is that which...

Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1806 - 320 pages
...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...stands on the other is called a perpendicular to it. _____ VIII, Book I. An obtuse angle is that which is greater than a right angle. IX. An acute angle...

Pantologia. A new (cabinet) cyclopædia, by J.M. Good, O. Gregory ..., Volume 5

John Mason Good - 1813 - 714 pages
...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...other is called a perpendicular to it. 11. An obtuse an¿le is that which is greater 'than a right angle. IS. An acnte angle is that which is less than...

Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Circle-squaring - 1819 - 350 pages
...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...stands on the other is called a perpendicular to it. VIII. An obtuse angle is that which is greater than a right angle. An acute angle is that which is...

Pantologia. A new (cabinet) cyclopædia, by J.M. Good, O. Gregory ..., Volume 5

John Mason Good - 1819 - 800 pages
...adjacent angles equal to one another, each of (lie angles is called и right angle; and the ira glu line which stands on the other is called a perpendicular to it. 11. An obtuse angle is that which is g cater than a right an^le. 12. Ли acute angle is that which ¡s less than a ri^ht angle. 13. " A...

The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh ...

Euclid, Robert Simson - Geometry - 1821 - 514 pages
...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. XI. An obtuse angle is that which is greater than a right angle. XII. An acute angle...

A Popular Course of Pure and Mixed Mathematics ...: With Tables of ...

Peter Nicholson - Mathematics - 1825 - 1046 pages
...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...angle is that which is greater than a right angle. ^ 12. An acute angle is that which is less than a right angle. 13. " A term or boundary is the extremity...

Elements of Arithmetic, Algebra, and Geometry

George Lees - 1826 - 276 pages
...on another straight line CD, makes the adjacent angles ABC and ABD equal to one another, each of the angles is called a right angle, and the straight line,...stands on the other, is called a perpendicular to it. •D OF GEOMETRY. with another CD, upon one side of it, are eitlier two right angles, or are, together,...