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When a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right, and the straight line standing on the other is called a perpendicular to that on which it stands.
Euclid's Elements of Geometry: The First Six, the Eleventh and Twelfth Books - Page 18
by Euclid, Edmund Stone - 1765 - 464 pages

## Euclid's Elements of Geometry: From the Latin Translation of Commandine. To ...

John Keill - Logarithms - 1723 - 364 pages
...B. Wherefore the Angle AFE j. g ti fhall bef equal to the Angle BFE. But when a Right Line {landing upon a Right Line makes the adjacent Angles equal to one another, each of the equal Angles is ia Right Angle. Wherefore AFE, or BFE, is a Right Angle. And therefore the Right Line CD drawn thro*...

## Euclid's Elements of Geometry: From the Latin Translation of Commandine. To ...

John Keill - Trigonometry - 1733 - 397 pages
...Center G. Therefore the Angle * 8- i. AD G is * equal to the Angle GD B. But when a Right Line ftanding upon 'a Right Line, makes the adjacent Angles equal to one another, each of the 10. i. equal Angles will f be a Right Angle. Wherefore the Angle GDB is a Right Angle. But FDB is alfo...

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

Robert Simson - Trigonometry - 1762 - 466 pages
...the angle ADG is equal c to the angle GDB. but when a ftraight line ftanding upon another ftraight line, makes the adjacent angles equal to one another ,each of the angles is a right angle *. therefore the angle GDB is a right angle. but FDB is like- d.io.Def.i. wife...

## Euclid's Elements of Geometry: From the Latin Translation of Commandine. To ...

John Keill - Logarithms - 1772 - 399 pages
...B. Wherefore the Angle AFE fliall be f equal to the Angle BFE. But when af 8. t. Right Line Standing upon a Right Line makes the adjacent Angles equal to one another, each of the equal Angles is J a Right Angle. Wherefore AFE, orJ0«/. 10. i« BFE, is a Right Angle. And therefore the Right •Line...

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

Robert Simson - Trigonometry - 1775 - 520 pages
...placed at that point; « as the angle at li.' X. When a ftraight line flanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which flands on the other is called a perpendicular...

## The Elements of Euclid: With Dissertations Intended to Assist and Encourage ...

Euclid, James Williamson - Euclid's Elements - 1781 - 309 pages
...8. i.) the angle AFE is equal to the angle BFE : but when a ftraight line ftanding upon a ftraight line makes the adjacent angles equal to one another, each of the equal angles is a right angle ; therefore each of the angles AFE, BFE is a right angle : therefore CD through the center cutting...

## The First Six Books: Together with the Eleventh and Twelfth

Euclid - 1781 - 520 pages
...'letter placed at that point; as the Angle at E.' .X. When a ftraight line flanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which ftands on the other is called a perpendicular...

## Euclid's Elements of Geometry: From the Latin Translation of Commandine, to ...

John Keill - Logarithms - 1782 - 399 pages
...Centre G. Therefore the Angle ADG is * equal to the Angle GD B. But when 3*8.,. Right Line ftandmg upon a Right Line makes the adjacent Angles equal to one another, each of the equal Angles will f be a Right Angle. Wherefore fZ?»/.io.» F the the Angle GDB is a Right Angle. But FDB is alfo...