 | Geography - 1867 - 964 pages
...angles. OüTUSE-ütOLSD, Having one obtuse angle, and, of necessity, twoacuteangles. Now, as the three interior angles of a triangle are together equal to two right angles or 180 degrees, and as an obtuse angle is any angle greater than a right angle or 90 degrees, while... | |
 | Sir John Leslie - Geometry, Plane - 1809 - 522 pages
...THEOR. * • > An exterior angle of a triangle is equal to both its opposite interior angles, and all the interior angles of a triangle are together equal to two right angles. The exterior angle BCD, formed by the production of the side AC of the triangle ABC, is equal to the... | |
 | Edward Riddle - Nautical astronomy - 1824 - 572 pages
...of the arc which measures the angle А С В, will be equal to the radius of the circle. For as all the interior angles of a triangle are, together, equal to two right angles, (Theo. 24.) if А С В be the third part of two right angles, the remaining angles A and B will, together,... | |
 | Industrial arts - 1831 - 532 pages
...reasoning will clearly apply to every triangle of which one side (AD) is produced. Cor. 2. — The three interior angles of a triangle are together equal to two right angles. This follows, as in Euclid's 32nd. If, however, it be said that it is premature to state that the angles... | |
 | William Chambers, Robert Chambers - Encyclopedias and dictionaries - 1842 - 938 pages
...most remarkable propositions in the whole book, namely, the 32d, in which it is shown that the three interior angles of a triangle are together equal to two right angles. This important fact has already been examined, and therefore we have only to add that it was discovered... | |
 | Samuel Bailey - Logic - 1851 - 256 pages
...Euclid. THEOREM. An exterior angle of a triangle is equal to both its opposite interior angles, and all the interior angles of a triangle are together equal to two right angles. The exterior angle BCD formed by the production of the side AC of the triangle ABC, is equal to the... | |
 | William Somerville Orr - Science - 1854 - 534 pages
...formula — sin. A sin. B ein. C abc without reference to Euclid's demonstration. Thus, since the three angles of a triangle are together equal to two right angles, we have A + В + С = 180°. .-. sin. (А + В) = sn. (180° — С) = sin. C. Л sin. A cos. B + sin. B cos.... | |
 | James Maurice Wilson - Geometry - 1868 - 132 pages
...right angles, or the lines PQ, QR would not meet. This follows also from the theorem that the three interior angles of a triangle are together equal to two right angles. PROBLEM 7. Having given two angles and a side opposite to one of them, to construct the triangle. V... | |
 | Henry Raper - 1870 - 968 pages
...ABC; that is, ACD, which is made up of ACE and EC D, is equal to BAC and AB C. 127. PROP. The three interior angles of a triangle are together equal to two right angles (fig. No. 126). By the above proposition, ACD is equal to the sum of ABC and BAC. Add to each ACB;... | |
 | Euclid, Charles Peter Mason - Geometry - 1872 - 216 pages
...produced, the exterior angle is equal to the sum of the two interior and opposite angles; and the three interior angles of a triangle are together equal to two right angles. For the construction employed in this proposition we must be able to draw through a given point a right... | |
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... the three interior angles of a triangle are together equal to two right angles. 
