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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.
Elements of Geometry: Containing the First Six Books of Euclid, with a ... - Page 294
by John Playfair - 1846 - 317 pages

## Elementary Geometry: With Applications in Mensuration

Charles Davies - Geometry - 1850 - 218 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. 3) ; and...

## Elementary Geometry: With Applications in Mensuration

Charles Davies - Geometry - 1850 - 236 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. 3) ; and...

## Plane trigonometry. [With] Solutions of examples. Appendix &c., to adapt the ...

John William Colenso (bp. of Natal.) - 1851 - 382 pages
...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 и be the number of sides of any rectilineal figure, we have the sum of its n angles + 4 x...

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

Sir Henry Edward Landor Thuillier - Surveying - 1851 - 828 pages
...proved, " 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" or in other words that — In any rectilineal figure, the sum of all the interior angles, is equal...

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

sir Henry Yule - 1851 - 282 pages
...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...

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

Janet Taylor - Nautical astronomy - 1851 - 702 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,...

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

Euclides - 1852 - 48 pages
...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....

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

Euclides - 1852 - 152 pages
...Con. 1. All the interior angles of any rectilinear figure, BOOK I. together with four right angles, are equal to twice as many right angles as the figure has sides. For any rectilinear figure ABODE can be divided into as many triangles as the figure has sides, by...