 Thus when it is said that 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.  Elements of Mechanical Drawing - Page 22by Gardner Chace Anthony - 1894 - 98 pagesFull view - About this book
 | Adelia Roberts Hornbrook - Geometry - 1895 - 222 pages
...straight line. How many degrees are there in the sum of all the angles ? PRINCIPLE 19. — The siwn of the angles of any triangle is equal to two right angles, or 180 degrees. 45. Draw different kinds of triangles, and repeat the process given in Ex. 44- illustrating... | |
 | Harvard University - Geometry - 1899 - 39 pages
...line is perpendicular to one of two parallel lines, it is perpendicular to the other. THEOREM XIX. The sum of the three angles of any triangle is equal to two right angles. THEOREM XX. The sum of the angles of a polygon of n sides is 2n — 4 right angles. THEOREM XXI. If... | |
 | Education - 1899 - 508 pages
...problem; (g) a theorem; (h) a hypothesis; (i) a corollary; (j) a postulate. 1 credit each. 3. Demonstrate: The sum of the three angles of any triangle Is equal to two right angles. 10 credits. 4. Demonstrate: If in any triangle a line be drawn from any angle to the middle of the... | |
 | William Wade Fitzherbert Pullen - Mechanics - 1902 - 436 pages
...satisfy himself of their accuracy by drawing the figures to scale, and testing by actual measurement. (1) The sum of the three angles of any triangle is equal to two right angles or 180°. (2) The opposite angles between a pair of intersecting straight lines are equal. In Fig. i the angle... | |
 | Alfred Baker - Geometry - 1903 - 154 pages
...exterior angle of any triangle is greater than either of the interior and opposite angles. Also, since the sum of the three angles of any triangle is equal to two right angles, the sum of any two angles of a triangle is less than two right angles. We may, however, by elongating... | |
 | Jonathan Rigdon - English language - 1903 - 312 pages
...propositions, but in subordinate propositions it does not always hold. " The earth is a sphere," and " The sum of the three angles of any triangle is equal to two right angles," are correct sentences; but "Columbus believed that the earth is a sphere," and " Some old mathematician... | |
 | Gordon Augustus Southworth, John Charles Stone - Arithmetic - 1904 - 334 pages
...measuring with a protractor or by cutting off and laying the angles together that — The sum of all the angles of any triangle is equal to two right angles, or 180 degrees. 7. How many right angles may a triangle contain ? How many obtuse ? How many measuring 60°... | |
 | Arthur Schultze - Algebra - 1905 - 674 pages
...area would be increased (a) 17, (b~) 917, (c) 415,673 square feet. Find the side of the square. 51. The sum of the three angles of any triangle is equal to 180°. The second angle equals three times the first, and the third angle 5 times the first: Find the... | |
 | Arthur Schultze - 1905 - 396 pages
...area would be increased (a) 17, (6) 917, (c) 415,673 square feet. Find the side of the square. 51. The sum of the three angles of any triangle is equal to 180°. In a given triangle the second angle equals three times the first, and the third angle 5 times... | |
 | Arthur Schultze - Algebra - 1906 - 584 pages
...area would be increased (a) 17, (b) 917, (c) 415,673 square feet. Find the side of the square. 51. The sum of the three angles of any triangle is equal to 180°. In a given triangle the second angle equals three times the first, and the third angle 5 times... | |
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