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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

## Mensuration for Beginners: With Numerous Examples

Isaac Todhunter - Measurement - 1869 - 312 pages
...three times another angle, or four times another angle ; and so on. 8. 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...

## Elements of Geometry, Conic Sections, and Plane Trigonometry

Elias Loomis - Geometry - 1871 - 302 pages
...divided. Thus, the angle BCD is the sum of the two angles BCE, ECD ; and the angle ECD is the difiei ence between the two angles BCD, BCE. 10. When a straight...perpendicular to it. 11. An acute angle is one which is lew than a right angle. An obtuse angle is one which .'s greater than a right angle. 12. Parallel straight...

## Explanatory mensuration for the use of schools

Alfred Hiley - 1871
...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,...

## The Quadrature of the Circle: The Square Root of Two, and the Right-angled ...

William Alexander Myers - Circle-squaring - 1873 - 238 pages
...concentric circles ; *that is, having a common center, as at F. 14. When a straight line standing on another straight line makes the adjacent angles equal to one another, each of the angles is a right angle, and the straight line which stands on the other is called a perpendicular...

## The Acting Teacher's and Student's in Training Guide and Text Book for ...

Henry Major - Student teachers - 1873
...line. An angle is named from three or one letters, as ABC or B. X. When a straight line standing oil 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...

## Euclidian Geometry

Francis Cuthbertson - Euclid's Elements - 1874 - 349 pages
...respects, and.-. AE is =BE; (i. i) ( 14 ) 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. PROPOSITION VI. If two straight lines cut...

## The Quadrature of the Circle: The Square Root of Two, and the Right-angled ...

William Alexander Myers - Circle-squaring - 1874 - 207 pages
...concentric circles ; that is, having a common center, as at F. 14. When a straight line standing on another straight line makes the adjacent angles equal to one another, each of the angles is a right angle, and the straight line which stands on the other is called a perpendicular...

## The Elements of Euclid, containing the first six books, with a selection of ...

Euclides - 1874 - 342 pages
...therefore 1. The cmgle ADG is equal to the angle GDB (I. 8), but when a straight line standing upon another straight line makes the adjacent angles equal to one another, each of the angles is a right angle (I. Def. 10) ; therefore 2. The angle GDB is a right angle ; but FDB is...