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 444
ED,that is, EF= ED. BOOK XL PROP. 4. 423 Hence in the A dae, fae, since DA, AE, ED = FA, AE, EF respectively, .-. the _ DAE - the _ fae. That is, DA is perp. to AE. Similarly it may be shewn that DA is perp. to every st. line which meets it in the plane of AB, AC ; DA is perp. to this plane.… … Let the st. line EF be perp. to each of the st. linesAB, DC at E their point of intersection. Then shall EF be also perp, to the plane XY, in which AB andDC lie. Make EA, EC, EB, ED all equal, and join AD. BC.Through E in the plane XY draw any st. line cuttingAD and BC in G and H. Take any pt. F in…
Geometry · Mathematics
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