Elements of plane and solid free-hand geometrical drawing, with lettering; and some elements of geometrical ornamental design, including the principals of harmonic angular ratios, etc. In three parts ... for draughtsmen and artisans; and teachers and students of industrial and mechanical drawing (1878)
Warren, S. Edward (Samuel Edward), 1831-1909 · New York, J. Wiley & sons · leaf 130
and the rectangle whose diagonal makes angles of 18°and 72° with its sides. Second. We have found (Arts. 40, 41) that from these pri-mary triangles others are derived, and from these, in turn, a cor-responding series of rectangles proceed. 48. It is interesting next to note that most of the…
Geometrical drawing · Mechanical drawing
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