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 143
But if the side, OA, of the right angle, be taken as such radius, as indicatedby the arc Aa, the other side, AB, will be the natural tangent of the sameangle. PL.XI. … OUKVILINEAE GEOMETKIC BEAUTY. 109 5°. The triangle 11 a 0. Here,. Oa= 1 — i/s and a11 = ^ ,__. Then to find the an^le at 0 to a radius of 1, 1we must proceed as in 4°, whence \.—\ 1/3 : 1 :: ^ — : tang. aOir. 1 1That is, tang, a 0 11 = - ^^ _ VS ?^ l-iy3 2-1/3 24/3-3 — 2.15425 = the natural tangent…
Geometrical drawing · Mechanical drawing
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