 | George Johnston Allman - Geometry - 1889 - 266 pages
...Thales can be drawn from the preceding notices. First inference. — Thales must have known the theorem that the sum of the three angles of a triangle is equal to two right angles. Pamphila, in (d), refers to the discovery of the property of a circle that all triangles described... | |
 | George Irving Hopkins - 1891 - 210 pages
...side of a triangle is less than the sum of the other two, and greater than their difference. 98. The sum of the three angles of a triangle is equal to two right angles. Sug. Consult Theorems 58 and 87. 99. If one side of a triangle be extended, the exterior angle... | |
 | Seth Thayer Stewart - Geometry, Modern - 1891 - 422 pages
...triangle, formed by extending the sides in the same order, is equal to six right angles. PROP. XVII. The sum of the three angles of a triangle is equal to two right angles. PROP. XVIII. The sum of any two angles of a triangle is equal to the supplement of the third... | |
 | Jean-Jacques Rousseau - Education - 1892 - 424 pages
...the place of mathematical demonstration. No experimental process can ever establish the general truth that the sum of the three angles of a triangle is equal to two right angle?. We should not confound " geometrical recreations " with geometrical science.—(P.) f Isoperimetric... | |
 | Jean-Jacques Rousseau - Education - 1892 - 424 pages
...the place of mathematieal demonstration. No experimental process can ever establish the general truth that the sum of the three angles of a triangle is equal to two right angles. We should not confound " geometrical recreations " with geometrical science. — (P.) f Isoperimetric... | |
 | William Ezra Worthen - Architectural drawing - 1892 - 850 pages
...equal to the three angles of the triangle, and their sum is equal to two right angles. Therefore, the sum of the three angles of a triangle is equal to two right angles. On one side of a triangle (Fig. 50) construct a triangle equal to the first, with opposite... | |
 | Florian Cajori - Mathematics - 1893 - 478 pages
...axioms, and, in short, came to make perfect demonstrations. In this way he arrived unaided at the theorem that the sum of the three angles of a triangle is equal to two right angles. His father caught him in the act of studying this theorem, and was so astonished at the sublimity... | |
 | William C. Bartol - Geometry, Solid - 1893 - 106 pages
...lines cannot meet. 353. Any side of a triangle is less than the sum of the other two sides. 354. The sum of the three angles of a triangle is equal to two right angles. 355. Two triangles are equal in all respects when two sides and the included angle of the one... | |
 | John Tilden Prince - Arithmetic - 1894 - 254 pages
...point is equal to 360°. 6. The opposite angles made by two lines crossing each other are equal. 7. The sum of the three angles of a triangle is equal to two right angles. The sum of the angles of a polygon is equal to two right angles taken as many times as the... | |
 | Science - 1878 - 804 pages
...certain inferences. Locke explains it as follows: After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles because he apprehends the geometrical proof, he thus continues : " But another man who never... | |
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After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles... 
