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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

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

Euclides - 1853 - 146 pages
...together 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

Royal Military Academy, Woolwich - Mathematics - 1853 - 400 pages
...together 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....

## The first six books of the Elements of Euclid, with numerous exercises

Euclides - Geometry - 1853 - 176 pages
...together 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. Сод. 2. All the exterior angles of any rectilineal figure are together equal to four right ,ingles....

## The Elements of Euclid: With Many Additional Propositions ..., Part 1

Euclid - Geometry - 1853 - 176 pages
...There are formed as many triangles as the figure has sides, therefore all their angles taken together are equal to twice as many right angles as the figure has sides (a) ; but the angles at the point F are together equal to four right angles (4), therefore all the...

## The popular educator, Volumes 5-6; Volume 8

Popular educator - 1854 - 940 pages
...divide it into three equal parts. *"'t 3Fig. .42. No. 3. interior angles together with four right angles are equal to twice as many right angles as the figure has sides. Therefore all the interior angles together with all the exterior angles are equal (Ax. 1) to all the...

## A Manual for Practical Surveyors

E. W. Beans - Surveying - 1854 - 114 pages
...taken. If the entire survey has been made as above directed, the sum of all the internal angles will be equal to twice as many right angles as the figure has sides, diminished by four right angles. If this sum, as in practice will be likely to be the case, should...

## Elements of Geometry and Trigonometry from the Works of A.M. Legendre ...

Charles Davies - Geometry - 1854 - 436 pages
...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 right...

## A Treatise on Land-surveying: Comprising the Theory Developed from Five ...

Surveying - 1878 - 534 pages
...proposition of Geometry, that in any figure bounded by straight lines, the sum of all the interior angles is equal to twice as many right angles, as the figure has sides less two; since the figure can be divided into that number of triangles. Hence this common rule. "...