A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 144
endingin the same direction from the vertices,and AB and EF parallel, and extending inopposite directions from the vertices; then areABC and DEF supplements of each other. For, produce the two sides not parallel, ifnecessary, till they meet. Now, BHD is thesupplement of BHE by {131), BHE = the… … PROPOSITION T. 283, Theorem,—Iftioo angleshavetheir sides respectively perpendicular toeach other, the angles are either equal orsupplementary. Dem,—Let BA be perpendicular to EF orto EF, and BC to ED; then is ABC = DEF.For, through B draw BO and BN, respectivelyparallel to ED and EF; then by the…
Geometry · Trigonometry
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