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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 sidef. For any rectilineal figure ABCDE can be divided into as many triangles as the figure has sides, by drawing...
Elements of geometry: consisting of the first four,and the sixth, books of ... - Page 30
by Euclides - 1842

## Euclid's Elements of geometry, the first three books (the fourth, fifth, and ...

Euclides - 1846 - 272 pages
...internal, are equal to twice as many right angles, as there are sides of the figure ; but the internal with four right angles, are equal to twice as many right angles as there are sides of the figure (by Cor. 6) ; take away from both the internal angles, and the external...

## The English Journal of Education, Volume 1

Education - 1847 - 508 pages
...liquidation of it. In how many years will the debt be paid off? OEOMETBY AND TRIGOSO1IETBY. SECTION I. — 1. All the interior angles of any rectilineal figure,...twice as many right angles as the figure has sides. 2. Equal triangles, upon equal bases in the same straight line, and towards the same parts, are between...

## Minutes of the Committee of Council on Education, Volume 1

...liquidation of it. In how many years will the debt be paid off? GEOMETRY AND TRIGONOMETRY. SECTION I. 1. All the interior angles of any rectilineal figure,...equal to twice as many right angles as the figure hag sides. 2. Equal triangles, upon equal bases in the same straight line, and towards the same parts,...

## A Complete Treatise on Practical Land-surveying: In All Its Departments ...

Anthony Nesbit - Plane trigonometry - 1847 - 426 pages
...accuracy of the previous work. Moreover, since the sum of all the interior angles of any polygon is equal to twice as many right angles as the figure has sides, lessened by four ; as the given figure has five sides, the sum of all its interior angles must be 2x5...

## Elementary Course of Geometry ...

Charles William Hackley - Geometry - 1847 - 248 pages
...Hence it follows that the sum of all the inward angles of the polygon alone, A + B -f- C + D + E, is equal to twice as many right angles as the figure has sides, wanting the said four right angles. QED Corol. 1. In any quadrangle, the sum of all the four inward...

## The definitions, postulates, axioms, and enunciations of the propositions of ...

Euclides - 1848 - 52 pages
...opposite angles ; and the three ulterior angles of every triangle are together equal to two right angles. COR. 1. All the interior angles of any rectilineal...twice as many right angles as the figure has sides. COB. 2. All the exterior angles of any rectilineal figure, made by producing the sides successively...

## The first three books of Euclid's Elements of geometry, with theorems and ...

Euclid, Thomas Tate - 1849 - 120 pages
...triangles ; that is (Cor. 2. i. 15.), 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. COR. 2. All the exterior angles of any rectilineal figuro, are together equal to four right angles....

## Elements of Geometry and Conic Sections

Elias Loomis - Conic sections - 1849 - 252 pages
...(Prop. XXVII., BI), that is, as there are sides of the polygon BCDEF. Also, the angles of the polygon, together with four right angles, are equal to twice as many right angles as the figure has sides (Prop. XXVIII., BI); hence all the angles of the triangles are equal to all the angles of the polygon,...