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. The papers set at the professional preliminary examination - Page 10
by College of preceptors - 1882 ## Inductive Geometry, Or, An Analysis of the Relations of Form and Magnitude ...

Charles Bonnycastle - Geometry - 1834 - 631 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 - 513 pages
...CBA, BAC, ACB are equal to two right angles. Wherefore, " if a side of a triangle," &c. QED COR. 1. All the interior angles of any rectilineal figure,...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... ## 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
...three interior angles of every triangle are equal to two right angles. Which was to be proved. COR. I. All the interior angles of any rectilineal figure,...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 angles» 2. All the exterior angles of any rectilineal figure are to. gether equal... ## The First Six and the Eleventh and Twelfth Books of Euclid's Elements: With ...

Euclid, James Thomson - Geometry - 1837 - 390 pages
...therefore also the angles CBA, BAC, ACB are equal to two right angles. Wherefore, if a side, &c. Cor. 1. All the interior angles of any rectilineal figure,...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
...angles (1. 13) ; therefore also the angles CBA, BAC, ACB, are equal to two right angles. COR. 1. — All the interior angles of any rectilineal figure,...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... ## Lessons on Form: Or, An Introduction to Geometry, as Given in a Pestalozzian ...

Charles Reiner - Geometry - 1837 - 215 pages
...vertex of these triangles = 4 rt. /.s; therefore, the sum 01 the interior angles of any polygon is equal to twice as many right angles as the figure has sides less [minus] four. M.—If the number of sides be three, four, five, six, seven, &c., what is the sum... 