 | Euclides - Geometry - 1853 - 334 pages
...AED, BEC, BED are together equal (Ax. 2) to four right angles. Which was to be proved. COB. 2. — The angles made by any number of straight lines meeting in one point shall be together equal to four right angles. Let AB, AC, AD, AE, AF be any number of straight lines... | |
 | Popular educator - 1854 - 922 pages
...exterior angles of the figure would not he altered in their direction, whatever might be their number; but "all the angles made by any number of straight lines meeting in a point, are together equal to four right angles;" therefore all the exterior angles of any rectilineal... | |
 | Euclides - 1855 - 270 pages
...at a point, on one side of a straight line, are together equal to two right angles. Corollary 2. — All the angles made by any number of straight lines meeting in a point, are together equal to four right angles. Definition 1. — When two angles are together equal... | |
 | Elias Loomis - Conic sections - 1858 - 256 pages
...angles formed at the point of intersection, are together equal to four right angles. Cor. 2. Hence, all the angles made by any number of straight lines...one point, are together equal to four right angles. PROPOSITION VI. THEOREM. If two triangles have two sides, and the included angle of the one, equal... | |
 | Robert Potts - Geometry, Plane - 1860 - 380 pages
...equal to the angle AED. Therefore, if two straight lines cut one another, &c. QED COB. 1. From this it is manifest, that, if two straight lines cut each...consequently that all the angles made by any number of lines meeting in one point, are together equal to four right angles. PROPOSITION XVI. THEOREM. If one... | |
 | Royal college of surgeons of England - 1860 - 332 pages
...the angles on the other side of the base shall be equal. 3. If two straight lines cut one another, the angles which they make at the point where they cut, are together equal to four right angles. 4. If a side of a triangle be produced, the exterior angle is equal to the two interior and opposite... | |
 | Popular educator - 1860 - 536 pages
...angles. Because if a straight line be drawn through the point, it is evident by the preceding corollary that all the angles made by any number of straight lines meeting in a point on the one side of that straight line, are equal to two right angles ; and all the angles made... | |
 | Euclides - 1862 - 172 pages
...lines, &c, QED Cor. 1. From this it is manifest, that, if two straight lines cut one another, the angles they make at the point where they cut, are together...consequently, that all the angles made by any number of lines meeting in one point, are together equal to four right angles. PROP. XVI.— THEOREM. If one... | |
 | Euclides - 1862 - 140 pages
...AED, are equal. Corollary. — 1. From this it is manifest that if two straight lines cut one another, the angles which they make at the point .where they cut, are together equal to four right angles. Corollary. — 2. And, consequently, that all the angles made by any number of lines meeting in one... | |
 | Evan Wilhelm Evans - Geometry - 1862 - 116 pages
...perpendicular to a third, they are parallel. • EXERCISES:1. Prove that the sum of all the adjacent angles made by any number of straight lines meeting in one point is equal to four right angles. 2. Prove that if one of the* four angles made by Evans' Geometry. —... | |
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if two straight lines" &c. QED COR. 1. From this it is manifest, that if two straight lines cut one another, the angles which they make at the point where they cut, are together equal to four right angles. 
