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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.
A Course of Mathematics: For the Use of Academies as Well as Private Tuition ... - Page 292
by Charles Hutton - 1831

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

Charles Davies - Geometry - 1886 - 334 pages
...twice as many right angles as the polygon has sidesBut the sum of all the interior angles together with four right angles, is equal to twice as many right angles as the polygon has sides (Th- xxi) : that is, equal to the sum of all the inward and outward angles taken...

## Elements of Geometry and Trigonometry

Adrien Marie Legendre - Geometry - 1852 - 436 pages
...right angles as the figure has sides, less four right angles (P. 26). Hence, the interior angles plus four right angles, is equal to twice as many right angles as the polygon has sides, and consequently, equal to the sum of the interior angles plus the exterior angles....

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

Euclides - 1852 - 148 pages
...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...

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

Euclides - 1852 - 44 pages
...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 Elements of Euclid: With Many Additional Propositions ..., Part 1

Euclid - Geometry - 1853 - 176 pages
...If a figure be rectilinear. Idem • . CONSEQUENCES. The sum of all the internal {angles, together with four right angles, is equal to twice as many right angles as the figure has sides. {All its external angles are together equal to four right angles. L. Relative to Circles generally....

## The Elements of Euclid. Books I.-VI.; XI. 1-21 XII. 1-2. A New Text ..., Book 1

Euclides - Geometry - 1853 - 334 pages
...similar. For if there be two regular polygons of the same number of sides, all the angles of each together with four right angles is equal to twice as many right angles as the polygon has sides ; and things that are equal to the same thing are equal to one another (Ax. i) :...

## The synoptical Euclid; being the first four books of Euclid's Elements of ...

Euclides - 1853 - 146 pages
...with four right angles. 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. COK. 2. — All the exterior angles of any rectilineal figure are together equal to four right angles....

## The geometry, by T. S. Davies. Conic sections, by Stephen Fenwick

...with four right angles. 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. COR. 2. All the exterior angles of any rectilineal figure are together equal to four right angles....