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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 and Conic Sections - Page 32
by Elias Loomis - 1857 - 226 pages

## Elements of geometry and mensuration

Thomas Lund - Geometry - 1854 - 192 pages
...angles as the polygon has sides. But the angles at 0 are equal to four right angles (30 Cor.); .'. all the angles of the polygon are equal to twice as many right angles as the polygon has sides, diminished by four right angles. COR. 1 . Hence, all the angles of a pentagon =...

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

Popular educator - 1854
...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...

## The Elements of geometry; or, The first six books, with the eleventh and ...

Euclides - 1855
...angles, and there are as many triangles in the figure as it has sides, all the angles of these triangles are equal to twice as many right angles as the figure has sides. But all the angles of these triangles are equal to the interior angles of the figure, viz. ABС, BСD,...

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

William Mitchell Gillespie - Surveying - 1855 - 436 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. "...

## Elementary text book for young surveyors and levellers

Henry James Castle - Surveying - 1856 - 185 pages
...angles are the exterior angles of an irregular polygon ; and as the sum of all the interior angles are equal to twice as many right angles, as the figure has sides, wanting four ; and as the sum of all the exterior, together with all the interior angles, are equal to four times...

## The elements of plane geometry, from the Sansk. text of Ayra Bhatta, ed. by ...

Āryabhaṭa - 1878
...been proved by the foregoing corollary, that all the interior angles together with four right angles are equal to twice as many right angles as the figure has sidesTherefore all the interior angles together with all the exterior angles are equal (Ax. 1) to all...