Text-book of Euclid's elements for the use of schools : books I - VI and XI (1900)
Hall, H. S. (Henry Sinclair), 1848-1934, Stevens, F. H. (Frederick Haller), 1853-1933 · MacMillan : London · leaf 449
n shall the st. line which joins E, F be in the same planeas AB, CD. For since AB and CD are par1,.*. they are in one plane. I. Def. 35. And since the points E and F are in this plane,.. the st. line which joins them lies wholly in this plane. I. Def. 7.That is, EF is in the plane of the parls AB,… … Let AB, CD be two par1 st. lines, of which AB is perp.to the plane XY. TJien CD shall also be perp. to the same plane. Let AB and CD meet the plane XY at the points B, D. Join BD :and in the plane XY draw DE perp. to BD, making DE equalto AB. Join BE, AE, AD. Then because AB is perp. to the plane…
Geometry · Mathematics
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