Books Books 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 Course of Mathematics: For the Use of Academies as Well as Private Tuition - Page 2
by Charles Hutton - 1812 ## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1835 - 316 pages
...together ; or, two quantities that are each of them equal to a third quantity, are equal to each other. 5. A Theorem is a demonstrative proposition ; in which...it is said that the sum of the three angles of any plane triangle is equal to two right angles, this is called a Theorem ; and the method of collecting... ## Annual Meeting of the American Institute of Instruction ..., Volume 5

American Institute of Instruction - Education - 1835 - 318 pages
...his 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.... ## Elements of Geometry: Containing the First Six Books of Euclid : with a ...

John Playfair - Geometry - 1837 - 332 pages
...or, two quantities that are each of them equal to a third quantity, are equal to each other. ,. if 5. A Theorem is a demonstrative proposition ; in which...it is said that the sum of the three angles of any plane triangle is equal to two right angles, this is called.a Theorem ; and the method of collecting... ## An Elementary Treatise on Plane and Solid Geometry

Benjamin Peirce - Geometry - 1837 - 159 pages
...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.... ## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1842 - 317 pages
...together ; or, two quantities that are each of them equal to a third quantity, are equal to each other. 5. A Theorem is a demonstrative proposition ; in which...it is said that the sum of the three angles of any plane triangle is equal to two right angles, this is called a Theorem; and the method of collecting... ## A Glance at the Physical Sciences, Or, The Wonders of Nature, in Earth, Air ...

Samuel Griswold Goodrich - Astronomy - 1844 - 370 pages
...be demonstrated, or something required to be done, and is accordingly either a theorem or a problem. A theorem is a demonstrative proposition, in which...when it is said that the sum of the three angles of a triangle is equal to two right angles, that is a theorem, the truth of which is demonstrated by geometry.... ## A Treatise on Algebra

Elias Loomis - Algebra - 1846 - 380 pages
...there are many other bipeds. (7.) A theorem is the statement of some property, the truth of which is required to be proved. Thus when it is said that the...theorem, the truth of which is demonstrated by Geometry. (8.) A problem is a question requiring something to be done. Thus, to draw one line perpendicular to... ## A Treatise on Algebra

Elias Loomis - Algebra - 1846 - 346 pages
...there are many other bipeds. (7.) A theorem is the statement of some property, the truth of which is required to be proved. Thus when it is said that the...theorem, the truth of which is demonstrated by Geometry. (8.) A. problem is a question requiring something to be done. Thus, to draw one line perpendicular... ## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1846 - 332 pages
...together ; or, two quantities that are each of them equal to a third quantity, are equal to each other. 5. A Theorem is a demonstrative proposition ; in which...it is said that the sum of the three angles of any plane triangle is equal to two right angles, this is called a Theorem; and the method of collecting... 