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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.
Elements of Geometry: Containing the First Six Books of Euclid, with a ... - Page 294
by John Playfair - 1846 - 317 pages

## The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh ...

Euclides - 1816 - 528 pages
...&c. QED COR. 1. 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. For any rectilineal figure ABCDE, can be divided into as many triangles as the figure has sides, by...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

Euclid, John Playfair - Circle-squaring - 1819 - 348 pages
...twice as many right angles as the figure has sides, wanting four. F°r. all the angles exterior and interior are equal to twice as many right angles as the figure has sides ; but the exterior are equal to four right angles ; therefore the interior are equal to twice as many...

## The First Six Books with Notes

Euclid - 1822 - 179 pages
...equal (i)Prop. 13. to two right angles (1), therefore all the external angles, with all the internal, are equal to twice as many right angles as the figure has sides ; but the internal angles, together with four right angles, are equal to twice as many rightangles...

## Euclid's Elements of Geometry: The Six First Books. To which are Added ...

Rev. John Allen - Astronomy - 1822 - 508 pages
...as many right angles, except four, as the figure has sides ; and all tbe angles of these triangles are equal to twice as many right angles as the figure has sides (32. 1 /CM.), therefore the angles of these triangles which are at their common vertex A, being those...

## Euclid's Elements of Geometry: The Six First Books. To which are Added ...

Rev. John Allen - Astronomy - 1822 - 516 pages
...two right angles [13. 1} ; therefore all the exterior and interior angles of the figure are together equal to twice as many right angles as the figure has sides ; but the interior angles are equal to twice as many right angles, except four, as the figure has sides...

## A Course of Mathematics: For the Use of Academies, as Well as Private ...

Charles Hutton - Mathematics - 1822 - 618 pages
...triangles, is equal to two right angles (th. 17) ; therefore 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, which are so / many of the angles of the triangles,...

## A treatise on navigation, and nautical astronomy

Edward Riddle - Nautical astronomy - 1824 - 572 pages
...angles as the figure has sides. But all the interior angles, and four right angles, are also together equal to twice as many right angles as the figure has sides, (Theo. 25.) Hence the interior and the exterior angles of the figure are, together, equal to the interior...

## A Popular Course of Pure and Mixed Mathematics ...: With Tables of ...

Peter Nicholson - Mathematics - 1825 - 372 pages
...QE I). Cor. 1 . All the interior angles of any rectilínea] figure, together with four right angles, are equal to 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...