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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, based on Euclid, book i - Page 23
by Edward Atkins - 1877

## The College Euclid: Comprising the First Six and the Parts of the Eleventh ...

Euclides - 1865 - 402 pages
...ECF; (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 ;' (def. 10) therefore each of the angles DCF, ECF, is a right angle. Wherefore, from the point C,...

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

Robert Potts - 1865 - 528 pages
...angle 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 the angle GDB is a right angle : but FDB is likewise a right...

## An English primer; compiled under the superintendence of E.C. Lowe

Edward Clarke Lowe - 1866 - 172 pages
...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 & perpendicular to it. 11. An obtuse angle is that which is greater than a right angle. 12. An acute...

## The Elements of Euclid for the Use of Schools and Colleges: Comprising the ...

Euclid, Isaac Todhunter - Euclid's Elements - 1867 - 424 pages
...angle ADG is equal to the angle BDG. [I. 8. 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 ; [I. Definition 10. therefore the angle BDG is a right angle. But the angle BDF is also a right angle....

## The Elements of Euclid for the Use of Schools and Colleges: Comprising the ...

Euclid, Isaac Todhunter - Euclid's Elements - 1867 - 426 pages
...angle ADG is equal to the angle BDG. [I. 8. But when a straight line, standing on another straight line, makes the adjacent angles equal to one another, each of the angle's is called "a right angle ; [I. Definition 10. therefore the angle BDG is a right angle. But...

## Modern Methods in Elementary Geometry

E. M. Reynolds - Geometry - 1868 - 172 pages
...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 perpendicular to it. We acquire a clear idea of'the magnitude of an angle by supposing it...

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

Robert Potts - 1868 - 434 pages
...angle 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 the angle GDB is a right angle : but FDB is likewise a right...

## Mensuration for Beginners: With Numerous Examples

Isaac Todhunter - Measurement - 1869 - 312 pages
...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,...stands on the other is called a perpendicular to it. Thus, in the figure, if the angle ABC is equal to the angle ABD each of them is a right angle, and...