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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 sidef. For any rectilineal figure ABCDE can be divided into as many triangles as the figure has sides, by drawing...
The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh ... - Page 39
by Euclid, Robert Simson - 1806 - 518 pages

## The Young Surveyor's Guide: Or, A New Introduction to the Whole Art of ...

Edward Laurence - Surveying - 1716 - 375 pages
...external < a, is equal to t wo right Angles (by tbe^tb /)confequently all the internal and external Angles are equal to twice as many right Angles as the Figure has fides. But all its internal Angles are equal to twiee as many right Angles eicept 4 as it has fides...

## The Young Gentleman's Arithmetick, and Geometry: Containing Such Elements of ...

Edward Wells - Arithmetic - 1723 - 294 pages
...the Sum of all the Angles in all the Tri~ angles, into which the Figure is divided, will together be equal to twice as ma-ny right Angles, as the Figure has Sides. But the Angles about P, the inward Point of each Figure, wherein all the Triangles concur, are (by...

## Euclid's Elements of Geometry: The First Six, the Eleventh and Twelfth Books

Euclid - Geometry - 1765 - 464 pages
...(for every whole ig equal to all its parts taken together) therefore .all the angles of a right-lined figure, together with four right angles, are equal to twice as many right angles as the figure has fides. And taking away four right angles from each, there will remain all the angles of the figure...

## A Royal Road to Geometry: Or, an Easy and Familiar Introduction to the ...

Thomas Malton - 1774 - 440 pages
...by the Sides. ie equal to four Right Angles. And, all the internal Angles of any Right-lined Figure are equal to twice as many Right Angles as the Figure has Sides, wanting four, (Th. i. i0. i.) confequently, the external Angles being equal to thofe four (Th. 2. of...

## The Elements of Euclid, Viz: The Errors, by which Theon, Or Others, Have ...

Robert Simson - Trigonometry - 1775 - 520 pages
...vertex of the triangles; that is", 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 fides. CoR. 2. All the exterior angles of any re&ilineal figure, are together equal to four right angles....

## The First Six Books: Together with the Eleventh and Twelfth

Euclid - 1781 - 520 pages
...vertex of the triangles; that isa, together with four right angles. Thprefpre all the angles of the figure, together with four right angles, are equal to twice as many right angles as the figure has fides. CoR. 2. All the exterior angles of any rectilineal figure, arc together equal to four right...

## A Complete Treatise on Practical Mathematics: Including the Nature and Use ...

John McGregor (teacher of mathematics.) - Mathematics - 1792 - 431 pages
...angles of any regular polygon* 3By cor. i ft, I. 32. Euclid. All the anterior angles of any reoilineal figure, together with four right angles, are equal to twice as many right angles as the figure has fides. Hence the following rule. RULÉ. From double thé number of fides f übt vail: 4, and the remainder...

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

John Playfair - Euclid's Elements - 1795 - 400 pages
...vertex of the triangles : that is a, together witi four right angles. Therefore all the angles of the figure, together with four right angles, are equal to twice as many rigit angles as the fi rurehas fides. CoR. 2. All the exterior angles of any reftilineal figure an...