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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.
Euclid's Elements [book 1-6] with corrections, by J.R. Young - Page 41
by Euclides - 1838

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

Euclides - 1816 - 528 pages
...the triangles : that is a, together is. 1. with four right angles. Therefore all the angles of the figure, together with four right angles, are equal...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....

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

Euclid, John Playfair - Circle-squaring - 1819 - 348 pages
...to all the angles of the figure, together with four right angles, that is, the angles of the figure are equal to twice as many right angles as the figure has sides, wanting four. COR. 2. All the exterior angles of any rectilineal figure are tegether equal to four...

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

Euclid, Robert Simson - Geometry - 1821 - 514 pages
...equal to two right angles. Wherefore if a side of a triangle, &c. QED COK. 1. All the interior aigles of any rectilineal figure, together with four right angles, are equal to twice as many right E' angles as the figure has sides. For any rectilineal figure ABCDE can be divided into as many triangles...

## The Elements of geometry [Euclid book 1-3] in general terms, with notes &c ...

Euclides - 1821 - 294 pages
...angle. Cor. 6 AH the internal angles of any rectilineal figure together with four right angles are = to twice as many right angles as the figure has sides. For if yon assume any. point within the given figure and draw lines from each of the angles to it, the...

## The First Six Books with Notes

Euclid - 1822 - 179 pages
...therefore equal to B AE and EAC. Cor. 6. 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. Take any point F within the figure and draw the right lines FA, FB, FC, FD, and FE. There are formed...

## 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,...