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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 Arithmetic, Algebra, and Geometry - Page 132
by George Lees - 1826

## Inductive Geometry, Or, An Analysis of the Relations of Form and Magnitude ...

Charles Bonnycastle - Geometry - 1834 - 670 pages
...expressed as the following proposition : "The interior angles of any closed plane figure are together equal to twice as many right angles as the figure has sides, minus four right angles." 206. And as a second application of the principle in question, or, which...

## The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh ...

Euclid - 1835 - 540 pages
...&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 ABCDE can be divided into as many triangles as the figure has sides, by...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1835 - 336 pages
...equal to all the angles of the figure, together with four right angles, that is, the anhas gles of the figure are equal to twice as many right angles as the figure sides, wanting four. COR. 1. All the exterior angles of any rectilineal figure are togethe1" equal...

## Library of Useful Knowledge: Geometry plane, solid, and spherical [by Pierce ...

Mathematics - 1835 - 684 pages
...is equal to two right angles (2.) ; all the interior angles, together with all the exterior angles, are equal to twice as many right angles as the figure has angles. But all the exterior angles are, by the former part of the proposition, equal to four right...

## The Teacher's Assistant in the "Course of Mathematics Adapted to the Method ...

Mathematics - 1836 - 488 pages
...angles ; and the three interior angles of every triangle are equal to two right angles. Сон. 1. All the interior angles of any rectilineal figure...the figure has sides, wanting four right anglesť 2. All the exterior angles of any rectilineal figure are to. gether equal to four right angles. XXXIII....

## The Element of Geometry

John Playfair - Geometry - 1836 - 148 pages
...proved. COR. I. 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 ABCDE can be divided into as many triangles as the figure has sides, by...

## Elements of Geometry and Trigonometry

Adrien Marie Legendre - Geometry - 1836 - 394 pages
...taken as many times, less two, as the polygon has sides (Prop. XXVI.) ; that is, equal to twice ay many right angles as the figure has sides, wanting four right angles. Hence, the interior angles plus four right .. -i angles, is equal to twice as many right angles as...

## A Treatise on Mensuration for the Use of Schools

Commissioners of National Education in Ireland - Measurement - 1837 - 284 pages
...you go along, as also the angles. angles, A, B, C, &c. of the figure together, and their sum must be equal to twice as many right angles as the figure has sides, wanting four right angles. But when the figure has a re-enterant angle, as F, measure the external angle, which is less than two...