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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.
The papers set at the professional preliminary examination - Page 10
by College of preceptors - 1882

## The geometry, by T. S. Davies. Conic sections, by Stephen Fenwick

...CBA, BAC, ACB, are equal to two right angles. Wherefore, if a side of a triangle, etc. QED COR. 1. All the interior angles of any rectilineal figure,...with four right angles, are equal to twice as many D right angles as the figure has sides. E.«=^lT"\~~-^, \ 4C-\ For any rectilineal figure ABCDE can...

## The Elements of Euclid: With Many Additional Propositions ..., Part 1

Euclid - Geometry - 1853 - 136 pages
...6, 12, 24, &c., equal parts. COROLLARY 7. All the internal angles of any rectilineal figure (ABCDE), together with four right angles, are equal to twice as many right angles as the figure has sides. DEMONSTRATION. Take any point F within the figure, and draw the straight lines FA, FB, FC, FD, FE....

## The Elements of Euclid, books i-vi; xi. 1-21; xii. 1,2; ed. by H.J. Hose, Book 1

Euclides - Geometry - 1853
...the angles of the polygon together with four right angles. But all the angles of the polygon GHKLM together with four right angles are equal to twice as many right angles as the polygon has sides (i. 32. Cor. i), that is, as there are plane angles constituting the solid angle...

## Orr's Circle of the Sciences: The mathematical sciences

...angles of the triangle are = two right angles, .'. if a side of a triangle, &c. QED Сов. 1. — All the interior angles of any rectilineal figure, together with four right angles, are = twice as many right angles as the figure has sides. For, any rectilineal figure ABODE can be divided...

## The popular educator, Volumes 5-6; Volume 8

Popular educator - 1854
...tiungles are equal to twice as many right anales as the figure has sides. Therefore all the angles of the figure together with four right angles are equal to twice as many right ung'es as the figure has sides. Corollary 2. All the exterior angles of any rectilineal figure, made...

## A Manual for Practical Surveyors

E.W. Beans - 1854
...taken. If the entire survey has been made as above directed, the sum of all the internal angles will be equal to twice as many right angles as the figure has sides, diminished by four right angles. If this sum, as in practice will be likely to be the case, should...

## Elements of Geometry and Trigonometry from the Works of A.M. Legendre ...

Charles Davies - Geometry - 1854 - 432 pages
...triangles in the figure ; that is, as many times as there are sides, less two. But this product is equal to twice as many right angles as the figure has sides, less four right angles. Cor. 1. The sum of the interior angles in a quadrilateral is equal to two right...

## The Elements of geometry; or, The first six books, with the eleventh and ...

Euclides - 1855
...triangles are equal to twice as many right angles as the figure has sides. 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. СOR. 2. — All the exterior angles of any rectilineal figure, made by producing the sides successively...