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 Books Books 1 - 10 of 165 on After remarking that the mathematician positively knows that the sum of the three.... After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles... Introduction and books 1,2 - Page 218
by Euclid, Sir Thomas Little Heath, Johan Ludvig Heiberg - 1908 ## An Introduction to Algebra: Being the First Part of a Course of Mathematics ...

Jeremiah Day - Algebra - 1820 - 332 pages
...equations, though they may not be presented to us under the algebraic forms. Thus the proposition, that the sum of the three angles of a triangle is equal to two right angles, (Euc. 32. 1.) may be demonstrated, either in common language, or by means of the signs used... ## Dictionary of the Mathematical and Physical Sciences, According to the ...

James Mitchell - Mathematics - 1823 - 576 pages
...of a triangle is less than the sum, but greater than the difference of the other two sides. 3. Tlie sum of the three angles of a triangle is equal to two right angles; and the external angle formed by producing one of its sides is equal to the sum of the t\vu... ## The new practical builder, and workman's companion, Volume 2

Peter Nicholson - Building - 1823
...; but the sum of the two angles BAC, BAD, is equal to two right angles (theorem 1) ; therefore the sum of the three angles of a triangle is equal to two right angles. 80. COROLLARY 1. — If two angles of one triangle be equal to two angles of another triangle,... ## An Introduction to Algebra: Being the First Part of a Course of Mathematics ...

Jeremiah Day - Algebra - 1827 - 332 pages
...equations, though they may not be presented to us under the algebraic forms. Thus the proposition, that the sum of the three angles of a triangle is equal to two right angles, (Euc. 32. 1.) may be demonstrated, either in common language, or by means of the signs used... ## Elements of the Geometry of Planes and Solids: With Four Plates

Ferdinand Rudolph Hassler - Geometry - 1828 - 159 pages
...of the line, which have been proved to be together, equal to two right angles; therefore, also, the sum of the three angles of a triangle is equal to two right angles; as was to be demonstrated. Carol. When two angles of a triangle are given, the third angle... ## Elements of Trigonometry, Plane and Spherical: Adapted to the Present State ...

Charles William Hackley - Trigonometry - 1838 - 307 pages
...and the other equal to 105° 30', it will be easy to find the third angle, by recollecting that the sum of the three angles of a triangle is equal to two right angles (Geom. B. 1, Prop. 25,) or 180° ; therefore subtracting the sum of the two given, 47° + 105°... ## A System of Crystallography: With Its Application to Mineralogy

John Joseph Griffin - Crystallography - 1841 - 469 pages
...in any right-angled triangle, a either n or w be given, then n, c and w are all given ; because the sum of the three angles of a triangle is equal to two right angles. Hence: c = 90°; n = 00° — w ; and w = <JO° — • n. No. tiiven. Sought. Equations. Logarithmic... ## A System of Crystallography,: With Its Application to Mineralogy

John Joseph Griffin - Crystallography - 1841 - 489 pages
...in any right-angled triangle, either n or w. be given, then n, с and w are all given; because the sum of the three angles of a triangle is equal to two right angles. Hence: с = 90°; n = 90° — w ; and w = 90° — n. Т E.) OBLIQUE-ANGLED PLANE TRIANGLES.... ## Elements of Plane Geometry: For the Use of Schools

Nicholas Tillinghast - Geometry, Plane - 1844 - 96 pages
...is the sum of the two angles CBE, EBD, is equal to the sum of the two angles BAC, BCA. Cor. 1 . The sum of the three angles of a triangle is equal to two right angles ; for CBD-f-CBA is equal to two right angles (Prop. 1) ; now we have just seen that CBD is equal... 