 | John Playfair - Euclid's Elements - 1837 - 332 pages
...each to each, the third angles are also equal. Now, this being demonstrated, it is easy to prove that the three angles of any triangle are equal to two right angles. Let ABC be a triangle right angled at A, draw AD perpendicular to BC. The triangles ABD, ABC have the... | |
 | Society for the diffusion of useful knowledge - 1840 - 522 pages
...angles of a right angled triangle be equal to e right angle, it is readily shown that all the three anM5 of any triangle are equal to two right angles. It...not our intention to go fully into the objections lich have been made to this proof, or to Legendre's saers; all which may be found in the notes to Dr.... | |
 | Thomas Perronet Thompson - Great Britain - 1842 - 504 pages
...opposite, any triangle may be divided into two right-angled triangles ; from which it may be inferred that the three angles of any triangle are equal to two right angles. After this, the proposition conveyed in what is commonly called the 12th Axiom, may be proved in the... | |
 | John Playfair - Euclid's Elements - 1842 - 332 pages
...each to each, the third angles are also equal. Now, this being demonstrated, it is easy to prove that the three angles of any triangle are equal to two right angles. Let ABC be a triangle right angled at A, draw AD perpendicular to BC. The triangles ABD, ABC have the... | |
 | Robert Griffith Hatfield - Architecture - 1845 - 326 pages
...equal to the angle, C. The same can be proved of the opposite angles, B and D. 149. — Proposition. The three angles of any triangle are equal to two right angles. Let abc, (Fig. 106,) be a given triangle, with its sides extended to/, e, and d, and the line, eg,... | |
 | Euclid, John Playfair - Euclid's Elements - 1846 - 334 pages
...each to each, the third angles are also equal. Now, this being demonstrated, it is easy to prove that the three angles of any triangle are equal to two right angles. Let ABC be a triangle right angled at A, draw AD perpendicular to BC. The triangles ABD, ABC have the... | |
 | Thomas Penington Kirkman - Mathematics - 1852 - 236 pages
...arcs or angles whose sum is two right angles are said to be supplements of each other. By Prop. D, the three angles of any triangle are equal to two right angles ; whence it follows that (SOs) and (OSs) are complements. We have then proved in (A, B, C, D), since... | |
 | William Robert Gordon - 1855 - 192 pages
...knowledge is knowledge ; or, in other words, our certainty is certainty. When you have proved that the- three angles of any -triangle are equal to two right angles, there is an end of doubt ; because there are no materials for ignorance to work up into phantoms."... | |
 | Robert Wharton Landis - Annihilationism - 1859 - 532 pages
...knowledge of immutable and eternal truth, by a reference to geometrical theorems. For instance, that the three angles of any triangle are equal to two right angles is, and ever has been, and ever will be, true in this world and in every world. Nor can we conceive... | |
 | Elements, George Drysdale - 1861 - 622 pages
...when once set in motion, tend to move in a straight line, and with uniform velocity, for ever ; that the three angles of any triangle are equal to two right angles ; or that health depends on the proper discharge of the bodily functions. It is with laws of this kind... | |
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We wish to prove that The three angles of any triangle are equal to two right angles. Let... 
