| Thomas Grainger Hall - Geometry, Descriptive - 1841 - 214 pages
...straight lines be perpendicular to a plane, they shall be parallel to each other. Let AB, ci>, be -L. to the same plane; AB shall be parallel to CD. Let them meet the plane in BD : join BD: draw DE -i- to BD, and in the same plane with it: make DE= AB: join BE, AE, AD. Then... | |
| Euclides - 1842 - 316 pages
...BD, BE are in one and the same plane. Therefore, if three straight lines, &c. QED PEOP. VI. THEOR. IF two straight lines be at right angles to the same...lines AB, CD be at right angles to the same plane BDE : AB is parallel to CD. Let them meet the plane in the points B, D. Draw DE at right angles to... | |
| John Playfair - Euclid's Elements - 1842 - 332 pages
...the same plane. PROP. VI. THEOR. Two straight lines which are at right angles to the same plane, are parallel to one another. Let the straight lines AB, CD be at right angles to the same plane BDE ; AB is parallel to CD. Let them meet the plane in the points B, D. Draw DE at right angles to... | |
| Euclides - 1845 - 546 pages
...BC, BD, BE are in one and the same plane. Therefore, if three straight lines, &c. QED PROPOSITION VI. THEOREM. If two straight lines be at right angles...lines AB, CD be at right angles to the same plane. Then AB shall be parallel to CD. Let them meet the plane in the points B, D, and draw the straight... | |
| Euclid - Geometry - 1845 - 218 pages
...are in one and the same plane. Therefore, if three straight lines, &c. QED PROPOSITION VI. THEOR. — If two straight lines be at right angles to the same...lines AB, CD be at right angles to the same plane : AB is parallel to CD. Let them meet the plane, in the points B, D, and draw the straight line BD, to which... | |
| Scottish school-book assoc - 1845 - 444 pages
...below it. Wherefore the three |« BC, BD, BE, are in one and the same plane. PROPOSITION LXXXIL — THEOREM. If two straight lines be at right angles to the same plane, they shall he parallel to one another. Let the \s AB, CD be at i* Ls to the same plane ; AB is || CD. Let them... | |
| Euclid, James Thomson - Geometry - 1845 - 382 pages
...BC, BD, BE are all in the sam« plane. Therefore, if three straight lines, eSzc. PROP. VI. THEOR. — If two straight lines be at right angles to the same plane, they are parallel to one another. Let the straight lines AB, CD be at right angles to the same plane BDE... | |
| Euclides - 1846 - 292 pages
...straight lines, %c. QED PROP. VI. THEOR, If too straight lines be at right angles to the same plant, they shall be parallel to one another. Let the straight...AB shall be parallel to CD. Let them meet the plane in the points B, D, and join BD, to which draw DE at right angles, in the same plane ; make DE equal... | |
| Euclid, John Playfair - Euclid's Elements - 1846 - 334 pages
...the same plane. PROP. VI. THEOR. Two straight lines which are at right angles to the same plane, are parallel to one another. Let the straight lines AB, CD be at right angles to the same plane BDE ; AB is parallel to CD. Let them meet the plane in the points B, D. Draw DE at right angles to... | |
| Samuel Hunter Christie - 1847 - 172 pages
...4). Wherefore, if from the foot of the perpendicular, &c.: which was to be proved. PROP. XVII. THEOR. If two straight lines, be at right angles to the same...parallel to one another. Let the straight lines AB, CD (fig. 24), meeting the plane MN in the points B and D, be at right angles to it: AB shall be parallel... | |
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