Elements of geometry : containing the first six books of Euclid, with a supplement on the quadrature of the circle, and the geometry of solids : to which are added, Elements of plane and spherical geometry (1826)
Playfair, John, 1748-1819, Euclid · Philadelphia : Marot & Walter · leaf 292
BD, (by hypothesis,) therefore BR and BD are equal, which is im-possible; BD is therefore at right angles to CD. Hence the proposition, that if a straight line fall on two parallellilies, it makes the alternate anjjles equal, is Easily derived. Let … FH and GE be perpeiWlieular to CD, then they will be parallel to oueanother, and also at right angles to AB, and therefore FG and HE areequal to one another, by the last proposition. Wherefore in the tri-angles EFG, EFH, the sides HE and EF are equal to the sides GFand FE, each to each, and also…
Euclid's Elements · Geometry · Trigonometry
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