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Therefore all the angles of the figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
The Elements of Euclid; viz. the first six books, together with the eleventh ... - Page 30
by Euclides - 1814

## Plane trigonometry. [With] Solutions of examples

...15. It appears, from Euc. I. 32, Cor. 1, that ' all the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.' Hence if n be the number of sides of any rectilineal figure, we have the sum of its n angles +4 x 90°=...

## A Manual of Surveying for India, Detailing the Mode of Operations on the ...

Ralph Smyth, Sir Henry Edward Landor Thuillier - Surveying - 1851 - 718 pages
...one acute angle, gives the other angle. Cor. 3. All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides. For any rectilineal figure ABODE, can be divided into as many triangles as the figure has sides, by...

## An Epitome of Navigation and Nautical Astronomy, with Improved Lunar Tables ...

Janet Taylor - Nautical astronomy - 1851 - 621 pages
...being the two angles made by cne line meeting another. The sum of all the outward and inward angles, is equal to twice as many right angles as the figure has sides; but the sum of all the inward angles is equal to twice as man1 right angles as the figure has sides,...

## Fortification for officers of the army and students of military history

sir Henry Yule - 1851
...polygon may be found from the property of such figures, that the sum of the angles of any polygon is equal to twice as many right angles as the figure has sides, less four. The following technical terms require explanation : — A Salient Angle is one directed...

## The First Two Books of the Elements of Euclid ... with Additional Figures ...

Euclides - 1852
...that is a , together with four right angles. . 2 Cor Therefore all the angles of the figure, XT - *• together with four right angles, are equal to twice as many right angles as the figure has sides. [The triangle furnishes an instance of this, for all its angles are together equal to two right angles;...

## The Elements of Euclid [book 1] for beginners, by J. Lowres

Euclides - 1852
...the produced line to the end of the base. COB. 3. All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides. COB. 4. All the exterior angles of any rectilineal figure are together equal to four right angles....

## Elements of Geometry and Trigonometry: With Applications in Mensuration

Charles Davies - Geometry - 1886 - 324 pages
...triangles is equal to two right angles (Th. xvii) : hence, the sum of the angles of all the triangles is equal to twice as many right angles as the figure has sides. But the sum of all the angles about the point P is equal to four right angles (Th. ii. Cor. 4) ; and...

## ELEMENTS OF GEOMETRY AND TRIGONOMETRY

A. M. LEGENDRE - 1852
...triangles in the figure ; that is, as many times as there are sides, less two. But this product is equal to twice as many right angles as the figure has sides, less four right angles. Cor. 1. The sum of the interior angles in a quadrilateral, is equal to two...