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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.
The Elements of Euclid with Many Additional Propositions and Explanatory Notes - Page 32
by Eucleides - 1860

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

Euclides - 1853 - 146 pages
...2.) 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
...i.) 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
...triangle, &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 abСde, can be divided into as many triangles as the figure has sides, by...

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

Popular educator - 1854 - 922 pages
...the angles of the figure (Conit.) ; 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 (Ax. 1). QED The demonstration of Euclid's Cor. II. viz. "that all the exterior angles of any rectilineal...

## 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: Containing Methods Indispensably Necessary ...

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 - 270 pages
...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. "...