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 42
Ex. Y5. A rightangled trianglewith equal acuteangles of 45° each. This triangle possesses the property of being divided by a per-pendicular from its right angle to its opposite side, into twotriangles of the same shape as the original whole. This prop-erty makes its construction easy. Draw this… … Ex. 76. A triangle each of whose halves is a right angled PLANE FIGUEBS BOUNDED BY STRAIGHT LINES. 29 TTpro 3 6°—2. 36°- 90° triangle with acute angles of 36° and 54°and ||o=f. Also in the whole triangle r^/o=^. These ratiosbeing varied, while all of them are simple, the triangle is verypleasing…
Geometrical drawing · Mechanical drawing
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