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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 - 1849 - 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 - 184 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,...

## 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 - 588 pages
...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 - 400 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 Shrewsbury trigonometry

John Clement P. Aldous - 1874 - 104 pages
...There is one well-known angle by which angles may be measured. DBF. When one straight line standing on another straight line makes the adjacent angles equal to one another, each of these angles is called a Bight Angle. Now all right angles are equal to one another. So that any angle...

## A school Euclid, being books i. & ii. of Euclid's Elements, with notes by C ...

Euclides - 1874 - 120 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...