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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.
A course of practical geometry for mechanics - Page 9
by William Pease - 1843 - 68 pages

## The Young Mathematician's Guide: Being a Plain and Easy Introduction to the ...

John Ward - Mathematics - 1747 - 492 pages
...is, AC, and C J5, are Perpendicular to £> C, as well as -D, C is to /•j'r/W or both of them. g. An OBTUSE ANGLE is that which is greater than a Right Angle. Such is the Angle included between the Lines AC and n CB. 10. An ACUTE ANGLE is that ^_ which is lefs...

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

Robert Simson - Trigonometry - 1762 - 488 pages
...and the ltraight line which ftands on the other is called a perpendicular to it. • XI. An obtufe angle is that which is greater than a right angle. XII. An acute angle is that which is lefs than a right angle. XIII. " A term or boundary, is the extremity of any thing." XIV. A figure...

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

Robert Simson - Trigonometry - 1775 - 534 pages
...and the ftraight line which flands on the other is called a perpendicular to it. — XI. An obtufe angle is that which is greater than a right angle. XII. An acute angle is that which is lefs than a right angle. xin. " A term or boundary is the extremity of any thing." XIV. A figure is...

## The philosophical and mathematical commentaries of Proclus ... on the first ...

Proclus (Diadochus.) - 1788 - 350 pages
...and the infifting Right Line, is called a PERPENDICULAR to that upon which it ftands. DEFINITION Xf. An OBTUSE ANGLE is that which is greater than a RIGHT ANGLE. DEFINITION XII. But an ACUTE ANGLE, is that which is Icfs than a RIGHT ANGLE, THESE are the triple...

## The Elements of Euclid: Viz. the First Six Books, with the Eleventh and ...

Alexander Ingram - Trigonometry - 1799 - 374 pages
...angle ; and the ftraight line which ftands on the other is called a perpendicular to it. XI. An oUufe angle is that which is greater than a right angle. XII. An acute angle is that which is lefs than a right angle. XIII. Omitted. XIV. A figure is that which is inclofed by one or more boundaries....

## The Elements of Euclid: Also the Book of Euclid's Data ...cor. viz. The ...

Robert Simson - Trigonometry - 1804 - 530 pages
...ftraight line which ftands on the other is called a .perpendicular to it. / XI. An obtufe angle js that which is greater than a right angle. XII. An acute angle is that which is lefs than a right angle. XIII. " A term or boundary, is the extremity of any thing." XIV. A figure...

## The shipwright's vade-mecum [by D. Steel].

David Steel - 1805 - 392 pages
...is the angle of ABC. " I An (tht use Angle is that which is greater than a right A ' angle, as ABC. An Acute Angle is that which is less than a right angle, asDBC. By an ANGLE of ELEVATION is meant the angle contained between a line of direction, and any plane...

## A New and Enlarged Military Dictionary: Or, Alphabetical Explanation of ...

Charles James - English language - 1805 - 1236 pages
...side, and consequently the arches intercepted either way are equal to 90°, or the quarter of a circle. An Acute ANGLE, is that which is less than a right angle, or 90°. An Obtuse ANCLE, is that whicb is greater than a right angle. Adjacent ANGLES, are such as...