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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...
Yale University Entrance Examinations in Mathematics: 1884 to 1898 - Page 125
1898 - 208 pages

## New Practical Algebra: Adapted to the Improved Methods of Instruction in ...

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...

## Practical Logic: Or, The Art of Thinking

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...

## Elements of geometry, tr. by J. Kaines

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...

## Elements of Geometry

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...

## Elements of Geometry

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 in logic. By members of the Johns Hopkins university

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...

## THE JOURNAL OF SPECULATIVE PHILOSOPHY

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...

## The Journal of speculative philosophy: Ed. by Wm. T. Harris ..., Volume 18

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...