The American house-carpenter; a treatise upon architecture, cornices and mouldings, framing, doors, windows, and stairs. Together with the most important principles of practical geometry (1852)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York : J. Wiley · leaf 65
122.— To draw a tangent to an ellipsis. Let abed, (Fig.38,) be the given ellipsis, and d the point of contact. Find thefoci, (Art. 115,)/and/, and from them, through d, draw/e andf d; bisect the angle, (Art. 77,) e d o, with the line, s r ; then5 r will be the tangent required. … 123.—An ellipsis with a tangent given, to detect the pointof contact. ~Letagbf, (Fig. 89,) be the given ellipsis and tan-gent. Through the centre, e, draw a b, parallel to the tangent;any where between e and/, draw c d, parallel to a b ; bisect c d ino ; through o and e, draw / g ; then g will be…
Carpentry · Architecture
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