American text books of art education : Geometrical drawing (1873)
Smith, Walter, 1836-1886 · Boston : James R. Osgood & Co. · leaf 84
,f^N Prob. 87.— To construct an ellipse, its diameters A B and C Dbeing giuen. Place A B and C D at right angles at their centres O. Find thefoci of the ellipse by taking half of A B as radius, and C as centre,cutting A B in F 1 and F 2. Divide the distance irom O to F 1 inparts decreasing towards…
Geometrical drawing
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![An illustration from Brief synopsis of the course of lectures in descriptive geometry; as arranged for the first year Faculty of Applied Science and Engineering, University of Toronto. [By] J. Roy Cockburn (1922)](https://img.insideoutlibrary.com/img/200/ia-fybriefsynopsiso00cockuoft-27-24.webp)
