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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.
New Elementary Geometry: With Practical Applications ; a Shorter Course Upon ... - Page 29
by Benjamin Greenleaf - 1873 - 176 pages

## A Manual of Surveying for India, Detailing the Mode of Operations on the ...

Ralph Smyth, Sir Henry Edward Landor Thuillier - Surveying - 1851 - 828 pages
...proved, " that 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" or in other words that — In any rectilineal figure, the sum of all the interior angles, is equal...

## Plane trigonometry. [With] Solutions of examples. Appendix &c., to adapt the ...

...Cor. 1, that ' 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.' Hence if и be the number of sides of any rectilineal figure, we have the sum of its n angles + 4 x...

## The Field Practice of Laying Out Circular Curves for Rail-roads

John Cresson Trautwine - Railroads - 1851 - 92 pages
...together all the internal angles, marked by dotted segments of circles; and subtract their sum from twice as many right angles as the figure has sides, less four, for the angle db e. Example. — Let the angles denoted by the dotted segments at the different letters...

## Elements of Geometry and Trigonometry

Adrien Marie Legendre - Geometry - 1852 - 436 pages
...are 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 angles multiplied...

## Elements of Geometry and Trigonometry: With Applications in Mensuration

Charles Davies - Geometry - 1886 - 334 pages
...triangles is equal to two right angles (Th. xvii) : hence, the sum of the angles of all the triangles is equal to twice as many right angles as the figure has sides. But the sum of all the angles about the point P is equal to four right angles (Th. ii. Cor. 4) ; and...

## The First Two Books of the Elements of Euclid ... with Additional Figures ...

Euclides - 1852
...1. All the interior angles of any rectilinear figure, BOOK I. together with four right angles, are equal to twice as many right angles as the figure has sides. For any rectilinear figure ABODE can be divided into as many triangles as the figure has sides, by...

## The Elements of Euclid [book 1] for beginners, by J. Lowres

Euclides - 1852
...base. COB. 3. 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. COB. 4. All the exterior angles of any rectilineal figure are together equal to four right angles....

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

Euclid - Geometry - 1853 - 136 pages
...rectilinear. Idem • . CONSEQUENCES. The sum of all the internal {angles, together with four right angles, is equal to twice as many right angles as the figure has sides. {All its external angles are together equal to four right angles. L. Relative to Circles generally....