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 147
= AC {= DF); then are the triangles equal. For, apply AC to its equalC F DF, the point A falling at D and C at F. Since A =D, AB will take the direc-tion DE. Let fall the per-pendicular FH upon DE, orDE produced. Now, CBbeing ^ DF, cannot fallbetween it and the perpen-dicular, but must fall in FDor… … 290. ScH. l.-If A and D are acute and CB {= FE) = AC {= DF), the tri-angles are isosceles. If A and D are right or obtuse, CB (=FE) must be greaterthan AC (= DF), in order that there may be a triangle, since the right or obtuseangle is the greatest angle in a triangle, and the greatest side is…
Geometry · Trigonometry
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