The American house-carpenter; a treatise on the art of building, and the strength of materials (1867)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York, J. Wiley · leaf 66
122.—To draw a tangent to an ellipsis. Let a 6 c d, {Fig.88,) 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: thens T will be the tangent required. … c Fig 89 123.—An ellipsis with a tangent given, to detect the pointof contact. Ijetagbf, {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/, drawc d,parallel to ab ; bisectcdin0 ; through o and e, draw/ ^ ; then g will be…
Carpentry · Architecture
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