Elements of geometry : containing books I to VI and portions of books XI and XII of Euclid, with exercises and notes (1881)
Smith, J. Hamblin (James Hamblin), 1829-1901, Kirkland, Thomas, 1835-1898 · Toronto : W.J. Gage · leaf 324
AB is± to BD and BE, .-. AB is± to the plane in which BD and BE are, XI. 4.and .•. AB is±to BF, a st. line in that plane. XI. Def. 2.Thus z ABF is a rt. i ,and z ABC is a rt. z ; Hyp. .■.iABC=iABF,the less = the greater, which is impossible. .. BC is not without the plane, in which BD, BE are,and… … I. 11 Let the st. lines AB, CD be J_ to the same plane. TJien must AB he \\ to CD.Let AB, CD meet the plane in the pts. B, D.Join BD, and draw DE a. to BD, in the same plane. :\Iake DE = AB, and join BE, AE, AD.Then •.• AB is±to the plane, .-. AB is ± to BD and BE, XL Def. 2. and .. each of the z s…
Geometry · Geometry, Plane
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