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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.
Euclid's Elements [book 1-6] with corrections, by J.R. Young - Page 41
by Euclides - 1838

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

Popular educator - 1854 - 940 pages
...tiungles are equal to twice as many right anales as the figure has sides. Therefore all the angles of the figure together with four right angles are equal to twice as many right ung'es as the figure has sides. Corollary 2. All the exterior angles of any rectilineal figure, made...

## 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 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...

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

Euclides - 1855 - 262 pages
...triangles are equal to twice as many right angles as the figure has sides. 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. СOR. 2. — All the exterior angles of any rectilineal figure, made by producing the sides successively...

## 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. "...

## Cambridge examination papers: a suppl. to the University calendar, 1856-59

Cambridge univ, exam. papers - 1856 - 200 pages
...also be equal. Prove this also without construction, by superposition. 3. Prove that all the internal angles of any rectilineal figure, together with four...twice as many right angles as the figure has sides; and that all the external angles are together equal to four right angles. In what sense are these propositions...

## The geometry of the three first books of Euclid, by direct proof from ...

Euclides - 1856 - 168 pages
...vertex of the triangles ; that is, together with four right angles. Therefore all the angles of the figure, together with four right angles, are equal...twice as many right angles as the figure has sides. XVI. If two triangles have two sides of the one equal to two sides of the other, each to each, and...

## The Popular Educator, Volume 5

1856 - 428 pages
...triangles thus formed are equal to all the angles of the figure (Const.) ; therefore all the angles of the figure, together with four right angles, are equal to twice as many right angles as the figure nas sides (Лх. 1). QED The demonstration of Euclid's Cor. II. viz. "that all the pxterior angles...