 | Francis Cuthbertson (geometer.) - 1876 - 102 pages
...is = the two angles BAC, ABC together. Wherefore if one side of a triangle &c. QED PROPOSITION XX. The three angles of a triangle are together equal to two right angles. Let ABC be a A. Then shall its three angles be together equal to two right angles. Produce BCtoD. Then... | |
 | E. S. Burchett - Geometry - 1876 - 188 pages
...study of Euclid should observe the following points, that may be culled from the First Book : — 1st. The three angles of a triangle are, together, equal to two right angles, invariably. 2nd. The triangle has the same number of equal sides that it has equal angles. 3rd. The... | |
 | Matthew R. Miller - Christianity and other religions - 1876 - 276 pages
...probably a horrible Inquisition would have flourished for a century, founded on the question whether the three angles of a triangle are together equal to two right angles. I have had some knowledge by personal experience of the unfairness of Universalists in their arguments... | |
 | Richard Wormell - 1876 - 268 pages
...XVIII. The exterior angle of any triangle is equal to the two interior and opposite angles together, and the three angles of a triangle are together equal to two right angles. Let А В С be a triangle of which А С D is the exterior angle ; then shall and Л С А В + ЛABC+... | |
 | 1878 - 958 pages
...and as we do so we discover that they have certain properties involved in their very nature, and that the three angles of a triangle are together equal to two right angles, and that parallel lines cannot meet. The properties of the ellipse, as demonstrated by Apollonius,... | |
 | Edward Harri Mathews - 1879 - 94 pages
...necessarily true as it stands ? Having completed the enunciation, prove the proposition. 3. Prove that the three angles of a triangle are together equal to two right angles ; and investigate the sum of the exterior angles of any plane convex polygon. 4. Show how to bisect... | |
 | Pupil teachers - 1880 - 1486 pages
...Proof.@Because the triangle ABD is equilateral, therefore the triangle ABD is equiangular (i. 5, Cor.) the three angles of a triangle are together equal to two right angles (i. 32), therefore the angle ABD is equal to a third of two right angles, that is, two-thirds of a... | |
 | Isaac Todhunter - Euclid's Elements - 1880 - 426 pages
...equilateral ; therefore the three angles EGD, GDE, DEG are equal to one another. [I. 5. Corollary. But the three angles of a triangle are together equal to two right angles; [I. 32. therefore the angle EGD is the third part of two right [Axiom 1. In the samp manner it may... | |
 | Henry Angel - 1880 - 360 pages
...When it equals that angle, the plane containing them is perpendicular to the hp This is obvious, as the three angles of a triangle are together equal to two right angles, and the lines have their greatest inclinations when they are contained by a vertical plane. The angle... | |
 | Henry Angel - Geometry, Plane - 1880 - 372 pages
...When it equals that angle, the plane containing them is perpendicular to the hp This is obvious, as the three angles of a triangle are together equal to two right angles, and the lines have their greatest inclinations when they are contained by a vertical plane. The angle... | |
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... the three angles of a triangle are together equal to two right angles, although it is not known to all. 
