Books Books
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 Plane Geometry: For the Use of Schools - Page 81
by Nicholas Tillinghast - 1844 - 96 pages

## Field and Colliery Surveying: A Primer Designed for the Use of Students of ...

Thomas Aloysius O'Donahue - Mine surveying - 1911 - 288 pages
...triangles may be grouped together to form an irregular polygon, and the interior angles should equal twice as many right angles as the figure has sides, less four right angles. Thus the interior angles of a ten-sided figure should total (10 x 2 — 4 = ) 16 right angles. Again,...

## 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...

## 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...

## 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...

## The Elements of Surveying and Geodesy

William Charles Popplewell - Geodesy - 1915 - 266 pages
...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
...angular 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 angles is equal to 2 x...

## 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 angles, or 360°. (8)...