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 167
tc. {24=2).Hence, ac : bd :: ce : df ::eg : fh. Secondly, if thesecant lines are not parallel,let them meet in some point,as O. Then, by the proposition, we have Oa : ac :: Ob : bd (1), and also Oc : ce :: Od : df (2). Taking the first by composition, it becomes Oa + ac : ac :: Ob + bd : bd, or Oc… … PROPOSITION n. 339, T7ieorein,—Con\eYse\y, If tiuo triangles have their cor-responding sides p)roportional, they are similar. Dem.—In the triangles ABC and DFE, let FD : CA :: FE : CB : : DE : AB ;then are the triangles similar. As one of the chai*acteristics of simi-larity, viz., proportionality…
Geometry · Trigonometry
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