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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.
Euclid's Elements [book 1-6] with corrections, by J.R. Young - Page 41
by Euclides - 1838

Elements of Arithmetic, Algebra, and Geometry

George Lees - 1826
...to all the angles of the figure, together with four right angles ; that is, the angles of the figure are equal to twice as many right angles, as the figure has sides wanting four. PROP. XIII. THEOREM. If two triangles, BAG, EOF, have two angles, BAG, ABC, and a side...

The Elements of Euclid: The Errors by which Theon, Or Others, Have Long ...

Robert Simson - Trigonometry - 1827 - 513 pages
...tri• 2 Cor. angles; that is * together with four right angles. There1s, 1. fore all the angles of the figure, together with four right angles, are equal...twice as many right angles as the figure has sides. COR. 2. All the exterior angles of any rectilineal figure are together equal to four right angles....

Elements of Geometry: With Notes

John Radford Young - Euclid's Elements - 1827 - 208 pages
...in each triangle amounts to two right angles, therefore the angles of all the triangles are together equal to twice as many right angles as the figure has sides, that is to say, the sum of the angles of the polygon, together with those about the point within it,...

The First Six Books of the Elements of Euclid, with a Commentary and ...

Euclid, Dionysius Lardner - Euclid's Elements - 1828 - 324 pages
...but the angles at the point F are equal to four right angles (83) ; and therefore the angles of the figure, together with four right angles, are equal...twice as many right angles as the figure has sides. This is the first corollary in the Elements, and the following is the second. (135) COR. 11. — The...

Elements of the Geometry of Planes and Solids: With Four Plates

Ferdinand Rudolph Hassler - Electronic book - 1828 - 159 pages
...angles, as AGD, GDE, and so on, standing in equal segments, are equal to one another; and their sum being equal to twice as many right angles as the figure has sides wanting four: that is, eight right angles, each of these angles of the hexagon is equal eight sixths...

Elements of Geometry: Being Chiefly a Selection from Playfair's Geometry

John Playfair - Geometry - 1829 - 186 pages
...twice — > -fQ as many right angles as there are sides of the figure. But all the interior angles together with four right angles are equal to twice as many right angles as there are sides of the figure (Prop. L). Therefore all the interior and all the exterior angles are...

The London Encyclopaedia: Or, Universal Dictionary of Science ..., Volume 10

...twice as 118 119 липу right angles as the figure has sides. Hence the interior angles of the figure are equal to twice as many right angles as the figure has sides wanting four right angles. Cor. 1. All the interior angles of a quadrilateral figure are together equal...

Geometry, Plane, Solid, and Spherical, in Six Books: To which is Added, in ...

Pierce Morton - Geometry - 1830 - 272 pages
...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...