| Physics - 1857 - 1142 pages
...first book of the ' Elements.' The proposition required by Euclid is the thirty-second, viz. that the **sum of the three angles of a triangle is equal to two right** angles ; given that proposition, the difficulty about parallels disappears, inasmuch as their properties... | |
| Josiah Lyman - Protractors - 1862 - 92 pages
...also the arc BD is the supplement of the arc AB ; and BCD is the supplement of the angle ACB. 11. The **sum of the three angles of a triangle is equal to two right** angles, or 180°. Hence, if the sum of any two angles of a triangle be subtracted from 180°, the remainder... | |
| Thomas Hill - Geometry - 1863 - 164 pages
...thr gles about the point A, and their sum is plainly two ! angles. 37. The mode of proving that the **sum of the three angles of a triangle is equal to two right** angles, by cutting a piece of card, is called experimental proof. It is of very little use in mathematics,... | |
| C. Davies - 1867 - 342 pages
...second, by Prob- VIII ; then will the angle HEF be equal to the third angle of the triangleFor, the **sum of the three angles of a triangle is equal to two right** angles (Bk- I- Th- xvii) ; and the sum of the three angles on the same side of the line DE fe equal... | |
| James Maurice Wilson - Geometry - 1868 - 132 pages
...it make the angles FGH=A, and HGK=B, then KGE will equal the third angle of the triangle, since the **sum of the three angles of a triangle is equal to two right** angles. At C and D make angles equal to HGK and KGE, and let their sides meet in O; then OCD is the... | |
| Public schools - 1869 - 794 pages
...great.y developed. For example, the child can be led to discover, by means of his protractor, that the **sum of the three angles of a triangle, is equal to two** right-angles, or that the vertical angles formed by the intersection of two lines, are equal. When... | |
| Trinity College (Hartford, Conn.) - 1870 - 1008 pages
...side of a triangle is less than the sum and greater than the difference of the other two sides. 2. The **sum of the three angles of a triangle is equal to two right** angles. 3. The diagonals of a parallelogram bisect each other. 4. An inscribed angle is measured by... | |
| Bowdoin College - Science - 1870 - 428 pages
...easy to gather every day, would be to deny a truth which in its way is as plainly shown as that the **sum of the three angles of a triangle is equal to two right** angles. If now it is announced to us that for the production of another kind of dropsy there is needed... | |
| Henry Barnard - Education - 1872 - 984 pages
...catch either into other cogged wheels, or into pinions, or into trundles, Ac. Of the Triangle. — The **sum of the three angles of a triangle is equal to two** right-angles, Ac. Of eimiiar Triangle*. — Two triangles are similar when the ingles of one ar» equal... | |
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