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Therefore all the angles of the figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
The Elements of Euclid; viz. the first six books, together with the eleventh ... - Page 30
by Euclides - 1814

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

Mathematics - 1835
...angle, 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...

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

John Playfair - Euclid's Elements - 1835 - 316 pages
...by -f of one right angle. PROP. XXVI. THEOR. All the interior angles of any rectilineal figure, art equal to twice as many right angles as the figure has sides, wanting four right angles. For any rectilineal figure ABCDE can be divided into as many triangles as...

## The Element of Geometry

John Playfair - Geometry - 1836 - 114 pages
...two right angles. Which was to be 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...

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

Mathematics - 1836 - 472 pages
...triangle are equal to two right angles. Сон. 1. All the interior angles of any rectilineal figure are equal to twice as many right angles as the figure has sides, wanting four right anglesť 2. All the exterior angles of any rectilineal figure are to. gether equal...

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

John Playfair - Geometry - 1837 - 318 pages
...angles of the figure are equal to twice as many right angles as the figure has sides, wanting four. COR. 2. All the exterior angles of any rectilineal...Because every interior angle ABC, with its adjacent exterior ABD, is equal (13. 1.) to two right angles ; therefore all the interior, together with all...

## The First Six and the Eleventh and Twelfth Books of Euclid's Elements: With ...

Euclid, James Thomson - Geometry - 1837 - 390 pages
...right angles. Wherefore, if a side, &c. 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 Plane Geometry According to Euclid

Andrew Bell - Euclid's Elements - 1837 - 240 pages
...ACB, are equal to two right angles. 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 be divided into as many triangles as the figure has sides, by drawing straight lines from a point F...

## A Treatise on Mensuration for the Use of Schools

Commissioners of National Education in Ireland - Measurement - 1837 - 262 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...