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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.
Elements of Geometry: Containing the First Six Books of Euclid, with a ... - Page 294
by Euclid, John Playfair - 1846 - 317 pages

## Mathematics, mechanics, heat

American School (Chicago, Ill.) - Engineering - 1903 - 392 pages
...ABCDEF oe the given polygon. To prove that the sum of the interior angles A, B, C, D, E, and F, is equal to twice as many right angles as the figure has sides minus two. If from any vertex as A, diagonals AC, AD, AE, are drawn, the polygon will be divided into...

## Elementary Plane Geometry: Inductive and Deductive

Alfred Baker - Geometry - 1903 - 154 pages
...From the result reached in the previous question, show that all the interior angles of any polygon are equal to twice as many right angles as the figure has angles (or sides), less four right angles. 5. How many right angles is the sum of all the angles in...

## A Text-book of Euclid's Elements for the Use of Schools, Book 1

Euclid - Euclid's Elements - 1904 - 488 pages
...1756. COROLLARY 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. Let ABCDE be any rectilineal figure. Take F, any point within it, and join F to each of the angular...

## The Colliery Manager's Handbook

Caleb Pamely - 1904 - 1238 pages
...for, " The sum of all the interior angles of any rectilinear figure, together with 4 right angles, are equal to twice as many right angles as the figure has sides." This is not so thorough a test as the plotting, because it checks only the angles taken and not the...

## A Treatise on Surveying, Volume 1

Reginald Empson Middleton - Surveying - 1904 - 332 pages
...angles as the figure has sides. The sum of the ' exterior ' angles diminished by four right angles is equal to twice as many right angles as the figure has sides. The sum of the ' differences of latitude ' being ' northings,' is equal to the sum of those which are...

## Introduction to Geometry: A Manual of Exercises for Beginners

William Schoch - Geometry - 1904 - 152 pages
...of a polygon without measuring them ? Exercise 33. If the sum of the interior angles of a polygon is equal to twice as many right angles as the figure has sides less four right angles, determine the sum of the interior angles of : 1. A six-sided polygon, or hexagon....

## A text-book of engineering drawing and design

Sidney Herbert Wells - Machine design - 1905 - 246 pages
...which says, that " the interior angles of any straight lined figure together with four right angles are equal to twice as many right angles as the figure has sides." The most common of the regular polygons used in engineering designs are the pentagon (five-sided),...

## Text Book of Topographical and Geographical Surveying

C. F. Close - Surveying - 1905 - 376 pages
...together with the line AB form an enclosed figure, and the sum of all the interior angles should be equal to twice as many right angles as the figure has sides, less four right angles. We thus have a check on the observed horizontal angles. It should be carefully...