 | Charles Hutton - Mathematics - 1812 - 620 pages
...which some property is asserted, and the truth of it required to be proved. Thus, when it is said that, The sum of the three angles of any triangle is equal to two right angles, this is a Theorem, the truth of which is demonstrated by Geometry. — A set or collection of such... | |
 | Charles Hutton - Mathematics - 1822 - 616 pages
...some property is asserted, and the truth of it required to be .proved. Thus, when it is said that, The sum of the three angles of any triangle is equal to two right angles, this is a Theorem, the truth of which is demonstrated by Geometry. — A set or collection of such... | |
 | American Institute of Instruction - Education - 1835 - 318 pages
...work, this author has pursued a different method in regard to parallel lines, by first proving that the sum of the three angles of any triangle is equal to two right angles ; but the demonstration is tedious and difficult for beginners, and is therefore rarely understood.... | |
 | Benjamin Peirce - Geometry - 1837 - 216 pages
...being perpendicular to its base, divides it, by art. 57, into the two equal triangles ABC and ABG. 64. Theorem. The sum of the three angles of any triangle is equal to two right angles. Demonstration. Let ABC (fig. 36) be the given triangle. Produce AC to D, and draw CE parallel to AB.... | |
 | Benjamin Peirce - Geometry - 1841 - 186 pages
...DF, and AB equal to DE. Place DE upon AB, EF will fall upon CB produced, since the right angles ABG and DEF are equal. An isosceles triangle CAG is thus...D, and draw CE parallel to AB. The angles ABC and DCE, being alternate-internal angles, are equal, and BAC and ECD, being externalinternal angles, are... | |
 | Elias Loomis - Algebra - 1846 - 376 pages
...statement of some property, the truth of which is required to be proved. Thus when it is said that the sum of the three angles of any triangle is equal to two right angles, this is a theorem, the truth of which is demonstrated by Geometry. (8.) A problem is a question requiring... | |
 | Elias Loomis - Algebra - 1846 - 380 pages
...statement of some property, the truth of which is required to be proved. Thus when it is said that the sum of the three angles of any triangle is equal to two right angles, this is a theorem, the truth of which is demonstrated by Geometry. (8.) A. problem is a question requiring... | |
 | Benjamin Peirce - Geometry - 1855 - 184 pages
...DF, and AB equal to DE. Place DE upon AB, EF will fall upon CB produced, since the right angles ABG and DEF are equal. An isosceles triangle CAG is thus...BCE, being alternate-internal angles, are equal, and J3AC and ECD, being externalinternal angles, are equal. Hence the sum of the three angles of the triangle... | |
 | Elias Loomis - Algebra - 1855 - 356 pages
...the statement of some property, the truth of which is required to be proved. Thus the principle that the sum of the three angles of any triangle is equal to two right angles, is a theorem, the truth of which is demonstrated by Geometry. (8.) A problem is a question requiring... | |
 | Horatio Nelson Robinson - Geometry - 1860 - 470 pages
...the theorem ; the sum of the angles of any parallelogram it eoual tc four right angles. THEOREM XI. The sum of the three angles of any triangle is equal to two right angles. Let AB C be a triangle, and through its vertex C / draw a line parallel to the b\e/a base AB, and produce... | |
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The sum of the three angles of any triangle is equal to two right angles. 
