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If a side of any triangle be produced, the exterior angle is equal to the two interior and opposite angles; and the three interior angles of every triangle are together equal to two right angles.
The calendar of the University college of Wales - Page lxxiv
by Wales univ, univ. coll. of Wales - 1878

## The Popular Educator, Volumes 1-2; Volume 12

Geography - 1867 - 964 pages
...в together make up the angle r> с в, which is therefore equal to the angles с в А, в A c. 7. The three interior angles of every triangle are together equal to two right anglet. In Fig. 5 the angle BCD has been shown to be equal to the angles с в А, в А с ; to each...

## The History of Philosophy, from the Earliest Times to the ..., Volume 1

William Enfield, Johann Jakob Brucker - Early works to 1800 - 1791 - 610 pages
...four. Of the geometrical theorems afcribed to Pythagoras, the following are the principal; that the interior angles of every triangle are together equal to two right angles; that the only polygons which will fill up the whole fpace about a given point, are the equilateral...

## General Biography: Or, Lives, Critical and Historical, of the Most ..., Volume 8

John Aikin - Biography - 1813 - 720 pages
...four. Of the geometrical theorems ascribed to Pythagoras, the following are the principal : that the interior angles of every triangle are together equal to two right angles ; that the only polygons which will fill up the whole space about a given point, are the equilateral...

## The History of Philosophy: From the Earliest Times to the ..., Volume 1

William Enfield - Philosophy - 1819 - 540 pages
...1. xiv. c, 33. "Boeth. deMus. 1. iv. c. 14. Pythagorjis, the following are the principal : that the interior angles of every triangle are together equal to two right angles ; that the only polygons Which will fill up the whole space about a given point, are the equilateral...

## A Treatise on Practical Gauging

Anthony Nesbit, W. Little - Measurement - 1822 - 916 pages
...produced to D ; the exterior angle ACD is equal to the two interior and opposite angles CAB, ABC; also the three interior angles of every triangle are together equal to two right angles. (Em. I. 32. Simp. I. 9, 10. Em. IL I, 2 J A C THEOREM V. Let the parallelograms ABCD, DBCEbe upon the...

## Geometry Without Axioms; Or the First Book of Euclid's Elements. With ...

Thomas Perronet Thompson - Euclid's Elements - 1833 - 150 pages
...And by parity of reasoning, the like may be proved in every other instance. Wherefore, universally, if the square described on one of the sides of a triangle, &c. Which was to be demonstrated. END OF THE FIRST BOOK. NOTES, FAMILIAR AND GEOMETRICAL. NOMENCLATURE...

## An Exposition of the Mysteries; Or, Religious Dogmas and Customs of the ...

John Fellows - Druids and druidism - 1835 - 432 pages
...four. Of the geometrical theorems ascribed to Pythagoras, the following are the principal: that the interior angles of every triangle are together equal to two right angles; that the only polygons which fill up the whole space about a given point, are the equilateral triangle,...

## The First Six and the Eleventh and Twelfth Books of Euclid's Elements: With ...

Euclid - Geometry - 1837 - 410 pages
...of any triangle be produced, the exterior angle is equal to the two interior and remote angles ; and the three interior angles of every triangle are together equal to two right angles. Let the side BC of the triangle ABC be produced to D : the exterior angle A CD is equal to the two...