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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.
The Elements of geometry; or, The first six books, with the eleventh and ... - Page 2
by Euclides - 1855

## Euclid's Elements [book 1-6] with corrections, by J.R. Young

Euclides - 1838 - 264 pages
...con'tained by DB.CB, is called the angle DBC, orCBD; but, ' if there be only one angle at a point, it may be expressed < by a letter placed at that point; as the angle at E.VIII. When a straight line standing on another straight line makes the adjacent angles equal to one...

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

Robert Simson - Geometry - 1838 - 434 pages
...equal (8. 1.) to the angle CHG; and they are adjacent angles ; but when a straight line standing on a straight line makes the adjacent angles equal to one another, each of them is a right angle, and the straight line which stands upon the other is called a perpendicular...

## First (Second) book of drawing (by J. Clark).

John Clark (drawing master.) - 1840 - 208 pages
...way. Vertical or Perpendicular Lines are those which are drawn perfectly upright. When a straight une standing on another straight line makes the adjacent angles equal to one another, then the upright une which stands on the other is called a perpendicular to it. The drawing of a perpendicular...

## The Elements of Euclid; viz. the first six books,together with the eleventh ...

Euclides - 1841 - 378 pages
...one angle at a point, it may be ' expressed by a le:ter placed at that point; as the ' angle at E." X. When a straight line standing on another straight...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...

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

John Playfair - Euclid's Elements - 1842 - 332 pages
...' BD, CB, is called the angle DBC, or CBD ; but, if there be only one an* gle at a point, it may be expressed by a letter placed at that point ; as the 'angle at E.' 7. When a straight line standing on another straight line makes the adjacent angles equal to one another,...

## Elements of geometry: consisting of the first four,and the sixth, books of ...

Euclides - 1842 - 320 pages
...by DB, CB is called ' the angle DBC, or CBD; but, if there be only one angle at ' a point, it may be expressed by a letter placed at that ' point ; as the angle at E.' X. When a straight line standing on another straight line makes the adjacent angles equal to one another,...

## A course of practical geometry for mechanics

William Pease - Geometry - 1843 - 80 pages
...' DB, CB, is called the angle DBG, or CBD ; but, if ' there be only one angle at a point, it may be expressed ' by a letter placed at that point ; as the angle at E.' 12. A Mixtilineal Angle is that which is contained by a right line and a curve. 13. A Spherical angle...

## A system of practical mathematics; being no.xvi. of a new series of school-books

Scottish school-book assoc - 1845 - 434 pages
...» only one angle at the point, as at E, it may be called simply the »ngle at E, PLANE GEOMETRY. 9. When a straight line standing on another straight...the adjacent angles equal to one another, each of the angles is called a right angle; and the strnight line which stands on the other is called a perpendicular...