The first six books of the elements of Euclid : with a commentary and geometrical exercises ; to which are annexed a treatise on solid geometry, and short essays on ancient geometrical analysis, and the theory of transversals (1861)
Lardner, Dionysius, 1793-1859 · London : Print. for Taylor and Walton · leaf 337
pplemental orexternal angle is the axis. El. (534). Theorem. (34) If two right lines F P, FP, diverging from a given point F, inter-sect two other right lines fp,fp, diverging from another given pointf, and the lines a c, a c, and ¥ f being drawn, right lines F b, fbfrom the given points F f, be… … In the triangle c F c the transversals c a, c a, F c intersect at thesame point. Hence (16) Fa.. F V. ,Fc. Therefore (32) fa, fb,fcare rays of an harmonic pencil whose axis is/F. In like manner inthe triangle fa c, the transversals/£, a c, a c intersect at the same APPENDIX III. 331 point bf. Hence…
Geometry
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