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... 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 within the figure to each of its angles.
The elements of plane geometry; or, The first six books of Euclid, ed. by W ... - Σελίδα 21
των Euclides - 1863
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## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

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...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...

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...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 Element of Geometry

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...straight lines from a point F within the figure to each of its angles. And, by the preceding proposition, all the angles of these triangles are equal to twice as many right angles as there are triangles, that is, as there are sides of the figure ; and the same angles are equal to the...

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

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...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 ...

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## Elements of Plane Geometry According to Euclid

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...straight lines from a point F within the figure to each of its angles. And, by the preceding proposition, all the angles of these triangles are equal to twice as many right angles as there are triangles ; that is, as there are sides of the figure ; and the same angles are equal to...

## Lessons on Form: Or, An Introduction to Geometry, as Given in a Pestalozzian ...

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...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...

## A Treatise on Mensuration for the Use of Schools

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...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...

## Elements of Geometry and Trigonometry

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...two right angles, taken as many times, less two, as the polygon has sides (Prop. XXVI.) ; that is, equal to twice as many right angles as the figure has sides, wanting four right angles. Hence, the interior angles plus four right angles, is equal to twice as...

## Euclid's Elements [book 1-6] with corrections, by J.R. Young

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...straight lines from a point F within the figure to each of its angles. And, by the preceding proposition, all the angles of these triangles are equal to twice as many right angles as there are triangles, that is, as there are sides of the figure : and the same angles are equal to the...