| James Bates Thomson - Algebra - 1880 - 324 pages
...on. Hence, the proposition must be universally true. 466. In Geometry, we have the proposition : TJie **sum of the three angles of a triangle is equal to two right** angles. We find it to be true in one case ; then in another, etc. Hence, we conclude the proposition... | |
| 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... | |
| 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... | |
| 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... | |
| 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... | |
| Antonio Rosmini-Serbati - 1885 - 668 pages
...mathematical affirmations — for example, "The consequence is contained in the principle," or " The **sum of the three angles of a triangle is equal to two right** angles " — then the copulative is signifies only ideal being. If the affirmation descends to the... | |
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