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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.
A Royal Road to Geometry: Or, an Easy and Familiar Introduction to the ... - Page 213
by Thomas Malton - 1774 - 440 pages

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

John William Colenso (bp. of Natal.) - 1851 - 382 pages
...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...

## An Epitome of Navigation and Nautical Astronomy, with Improved Lunar Tables ...

Janet Taylor - Nautical astronomy - 1851 - 702 pages
...being the two angles made by cne line meeting another. The sum of all the outward and inward angles, is equal to twice as many right angles as the figure has sides; but the sum of all the inward angles is equal to twice as man1 right angles as the figure has sides,...

## Fortification for officers of the army and students of military history

sir Henry Yule - 1851 - 282 pages
...polygon may be found from the property of such figures, that the sum of the angles of any polygon is equal to twice as many right angles as the figure has sides, less four. The following technical terms require explanation : — A Salient Angle is one directed...

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

Euclides - 1852 - 48 pages
...lines meeting in a point are equal to four right angles. 6. All the interior angles of any rectilineal figure, are equal to twice as many right angles as the figure has sides, less four right angles. 7. The exterior angles of a rectilineal figure are equal to four right angles....

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

Euclides - 1852 - 152 pages
...Con. 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...

## 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...

## Elements of Geometry and Trigonometry

Adrien Marie Legendre - Geometry - 1852 - 436 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...

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

Royal Military Academy, Woolwich - Mathematics - 1853 - 400 pages
...together with four right angles. 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. COR. 2. All the exterior angles of any rectilineal figure are together equal to four right angles....