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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 Arithmetic, Algebra, and Geometry - Page 132
by George Lees - 1826

## Elementary Course of Geometry ...

Charles William Hackley - Geometry - 1847 - 248 pages
...triangles is equal to two right angles (th. 15) ; therefore, 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 F, which are so many of the angles of the triangles,...

## A Complete Treatise on Practical Land-surveying: In All Its Departments ...

Anthony Nesbit - Plane trigonometry - 1847 - 492 pages
...accuracy of the previous work. Moreover, since the sum of all the interior angles of any polygon is equal to twice as many right angles as the figure has sides, lessened by four ; as the given figure has five sides, the sum of all its interior angles must be 2x5...

## The definitions, postulates, axioms, and enunciations of the propositions of ...

Euclides - 1848 - 52 pages
...angles. COR. 1. 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. 2. All the exterior angles of any rectilineal figure, made by producing the sides successively...

## Elements of Geometry and Trigonometry Translated from the French of A.M ...

Charles Davies - Trigonometry - 1849 - 372 pages
...to two right angles, taken as many times, less two, as the polygon has sides (Prop. XXVI.); that is, equal to twice as many right angles as the figure has sides, wanting four right angles. Hence, the interior angles plus four right Let the sides of the polygon ABCDFG, be produced, in the...

## The first three books of Euclid's Elements of geometry, with theorems and ...

Euclid, Thomas Tate - 1849 - 120 pages
...&c. QED COR. 1. 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...

## Elements of Geometry and Conic Sections

Elias Loomis - Conic sections - 1849 - 252 pages
...there are sides of the polygon BCDEF. Also, the angles of the polygon, together with four right angles, are equal to twice as many right angles as the figure has sides (Prop. XXVIII., BI); hence all the angles of the triangles are equal to all the angles of the polygon,...

## Reports on Elementary schools

Her MAjesty' Inspectors of schools - 1850 - 912 pages
...Section.) Section I. 1. 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. 2. If the square described upon one side of a triangle be equal to the sum of the squares described...

## The Church of England quarterly review, Volume 28

1850 - 524 pages
...proposition that all the interior angles of any rectilinear figure, together with four right angles, are equal to twice as many right angles as the figure has sides : and the dictum is equally true, too, in moral science — only in any particular case to dogmatize...