After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles... Introduction and books 1,2 - Page 218by Euclid, Sir Thomas Little Heath, Johan Ludvig Heiberg - 1908Full view - About this book
| George Johnston Allman - Geometry - 1889 - 237 pages
...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... | |
| Seth Thayer Stewart - Geometry - 1891 - 406 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... | |
| George Irving Hopkins - Geometry, Plane - 1891 - 179 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... | |
| Jean-Jacques Rousseau - Education - 1892 - 363 pages
...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... | |
| Appleton, firm, publishers, New York - Mechanical drawing - 1892 - 745 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... | |
| Jean-Jacques Rousseau - Education - 1892 - 355 pages
...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... | |
| WILLIAM C. BATOL, A.M., - 1893
...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 - 81 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
...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... | |
| Edwin Pliny Seaver, George Augustus Walton - Arithmetic - 1895
...it out. Tear off C FIG. 24. two of the angles and place them, as in Fig. 24, so as to show that The **sum of the three angles of a triangle is equal to two right** angles. e. How many degrees are there in each angle of an equilateral triangle ? /. If the two acute... | |
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