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Thus the proposition, that the sum of the three angles of a triangle is equal to two right angles, (Euc.
The first six books of the Elements of Euclid, and propositions i.-xxi. of ... - Page 295
by Euclides - 1885

## An Introduction to Algebra: Being the First Part of a Course of Mathematics ...

Jeremiah Day - Algebra - 1820 - 352 pages
...consist of a series of 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...

## The New Practical Builder and Workman's Companion, Containing a Full Display ...

Peter Nicholson - Architecture - 1823 - 210 pages
...; 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,...

## Dictionary of the Mathematical and Physical Sciences, According to the ...

James Mitchell - Mathematics - 1823 - 666 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...

## An Introduction to Algebra: Being the First Part of a Course of Mathematics ...

Jeremiah Day - Algebra - 1827 - 352 pages
...consist of a series of 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 - 180 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 - 328 pages
...to 47°, 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 Treatise on Geometry and Its Application in the Arts

Dionysius Lardner - Curves, Plane - 1840 - 386 pages
...of the adjacent internal angle. (51.) The following consequences flow obviously from the principle, that the sum of the three angles of a triangle is equal to 180° : — (52.) If one angle of a triangle is right, the sum of the other two is equal to a right...

## A System of Crystallography, with Its Application to Mineralogy

John Joseph Griffin - Crystallography - 1841 - 548 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...