 | Education - 1907 - 700 pages
...scientific accuracy is proverbial. It is susceptible of definite proof that two and two make four; that the, sum of the three angles of a triangle is equal to two right angles and nothing else. There need never be any question as to what will result when carbon burns... | |
 | Daniel Seely Gregory - Logic - 1881 - 236 pages
...best policy. 15. Education cannot be effected by mere class-room instruction or lecturing. 16. The sum of the three angles of a triangle is equal to two right angles. 17. Two straight lines cannot inclose a space. 18. The earth is between 93,000,000 and 94,000,000... | |
 | Alexis Claude Clairaut - 1881 - 184 pages
...opposite sides of a straight line which cuts two parallels ........ 36 These angles are equal 37 64. The sum of the three angles of a triangle is equal to two right angles 37 68. The exterior angle of a triangle is equal to the sum of its two interior opposite angles... | |
 | George Albert Wentworth - Geometry, Modern - 1881 - 266 pages
...perpendicular, each to each, they are either equal or supplementary. PROPOSITION XXI. THEOREM. 98. The sum of the three angles of a triangle is equal to two right angles. BE С Let AB С be a triangle. We are to prove ¿ B + ZB С A + ¿ A = two rt. A. Draw С E... | |
 | George Albert Wentworth - Geometry, Modern - 1882 - 268 pages
...perpendicular, each to each, they are either equal or supplementary. PROPOSITION XXI. THEOREM. 98. The sum of the three angles of a triangle is equal to two rig/'t angles. С Let ABC be a triangle. We are to prove Z. B + ZB С A + ZA = two rt. A. Draw С E... | |
 | Studies - Logic, Symbolic and mathematical - 1883 - 226 pages
...analysis of the nature of probability. 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 then continues : " But another man who never... | |
 | Philosophy - 1884 - 462 pages
...negation ; and, of course, what is true of triangle is true of all general ideas ; they are negations. The sum of the three angles of a triangle is equal to two right angles. This is a proposition to be demonstrated. I draw a triangle, and prove that the three angles... | |
 | WILLIAM T HARRIS - 1884 - 482 pages
...negation ; and, of course, what is true of triangle is true of all general ideas ; they are negations. The sum of the three angles of a triangle is equal to two right angles. This is a proposition to be demonstrated. I draw a triangle, and prove that the three angles... | |
 | Euclid, John Casey - Euclid's Elements - 1885 - 340 pages
...B. LEGENDRE'S AND HAMILTON'S PROOFS or EUCLID, i. xxxn. The discovery of the Proposition that "the sum of the three angles of a triangle is equal to two right angles ' ' is attributed to Pythagoras. Until modern times no proof of it, independent of the theory... | |
 | Euclides - 1885 - 340 pages
...two angles ABC, CDA equal to the sum of the three angles ACD, DAC, CDA of the triangle ACD ; but the sum of the three angles of a triangle is equal to two right angles [I. xxxn.]. Therefore the sum of ABC, CDA is two right angles. Or thus : Let O be the centre... | |
| |
After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles... 
