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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 ...: Composed for the Use of the Royal Military ... - Page 2
by Charles Hutton - 1811

## A Course of Mathematics: In Two Volumes : for the Use of Academies, as Well ...

Charles Hutton - Mathematics - 1816
...Definitions, Axioms, Propositions, Theorems, Problems, Lemmas, Corollaries, Scholiums, &c. 4. . / Dijinition is the explication of any term or word in a science...The sum of the three angles of any triangle is equal lo two right angles, this is a Theorem, the truth of which is demonstrated by Geometry. —A set or...

## A Course of Mathematics: For the Use of Academies, as Well as Private Tuition

Charles Hutton - Mathematics - 1818 - 646 pages
...Definition ought to be clear, and expressed in words that are common and perfectly well understood. 6. A Proposition is something proposed to be proved,...of which is demonstrated by Geometry. — A set or collector! of such Theorems constitutes a Theory. 7. A. Problem is a proposition or a question requiring...

## A Course of Mathematics: For the Use of Academies, as Well as Private ...

Charles Hutton - Mathematics - 1822 - 618 pages
...Definition ought to be clear, and expressed in words that are common and perfectly well understood. 6. A Proposition is something proposed to be proved,...collection of such Theorems constitutes a Theory. I. A Problem is a proposition or a question requiring •something to be done ; either to investigate...

## A Course of Mathematics: For the Use of Academies as Well as Private Tuition ...

Charles Hutton - Mathematics - 1831
...are common and perfectly well understood. 5. A Proposition is something proposed to be demonstrated, or something required to be done ; and is accordingly...when it is said that, The sum of the three angles of a plane triangle is equal to two right angles, that is a Theorem, the truth of which is demonstrated...

## 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

...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 - 318 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....