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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.
A Course of Mathematics: For the Use of Academies as Well as Private Tuition ... - Page 292
by Charles Hutton - 1831

## Annual Report of the Department of Education ..., Volume 4, Part 1911; Volume 6

Alberta. Department of Education - Education - 1912 - 244 pages
...8. Prove that 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. 8 9. (a) If a straight line be bisected and produced to any point, the rectangle contained by the whole...

## Special Reports on Educational Subjects, Volumes 26-27

Great Britain. Board of Education - Education - 1912 - 1048 pages
...BC. 2. Prove that the interior angles of any rectilinear figure together with four right angles are equal to twice as many right angles as the figure has sides. Find the number of sides of a regular polygon, each angle of which is equal to the sum of an angle...

## The Teaching of Mathematics in the United Kingdom

Great Britain. Board of Education - Mathematics - 1912 - 632 pages
...BC. 2. Prove that the interior angles of any rectilinear figure together with four right angles are equal to twice as many right angles as the figure has sides. Find the number of sides of a regular polygon, each angle of which is equal to the sum of an angle...

## The Elements of Surveying and Geodesy

William Charles Popplewell - Geodesy - 1915 - 266 pages
...the number of sides. Stated precisely, " the sum of all the internal angles of a closed polygon plus four right angles is equal to twice as many right angles as the figure has sides." So that it is easy from the field notes to find the internal angle at each corner of the figure, and...

## Surveying and Building Construction for Agricultural Students, Land Agents ...

Alfred Hubert Haines, A. F. Hood Daniel - Building - 1915 - 360 pages
...fulfilled :— 1. All the interior deduced or observed angles together with four right angles must be equal to twice as many right angles as the figure has sides. 2. The northings must equal the southings. 3. The eastings must equal the westings. In ordinary traverse...

## Surveying as Practised by Civil Engineers and Surveyors: Including the ...

John Whitelaw - Surveying - 1916 - 578 pages
...measurements before leaving the ground, as " the sum of the interior angles of any rectilinear figure is equal to twice as many right angles as the figure has sides, less four right angles." In the case of Fig. 73, as the figure is four-sided the sum of the interior...

## The Founder's Manual: A Presentation of Modern Foundry Operations, for the ...

David Wells Payne - Founding - 1917 - 724 pages
...opposite to corresponding angles are proportional. (6) In any polygon, the sum of all the interior angles is equal to twice as many right angles as the figure has sides, less four right angles. (7) In any polygon the sum of all the exterior angles is equal to four right...

## A Text-book of Theodolite Surveying and Levelling: For the Use of Students ...

James Park - Azimuth - 1922 - 598 pages
...iii . . . . 141 12 iv .... 66 40 Total . 360° 00' And the sum of the internal angles of a polygon is equal to twice as many right angles as the figure has sides, less four right angles. Our figure has four sides, .-. 90(4x2) -(4x90) =360°, which agrees with the...