The elements of navigation : containing the theory and practice, with all the necessary tables, to which is added, a treatise of marine fortification ... (1754)
Robertson, J. (John), 1712-1776, Adams, Charles Francis, 1807-1886, former owner. BRL, Adams, John, 1735-1826, former owner. BRL, Boston Public Library) John Adams Library BRL · London : Printed for J. Nourse ... · leaf 100
RY, n 285. THEOREM XXXIV. <fhefeclions (aebd) of a Cone or Pyramid (c A E BD ),which are parallel to the bafe (aebd), are fimilar tothat bafe. Dem. For let afbc, dfec, be fe&ions thro* thevertex c, and centre f of the bafe. Then thefe fections will cut one another in theright line fc (283),… … And the like in any other fe&ions thro*c and f. (24-8) fa :fa- :: fb :fb ::fd :fd : : fe :fe. Now in theCone, f a=fb=fd=fe ; therefore fa-=.fbr=fd=fe. (241)So that all the right lines drawn (romf to the circumference of the figureadbe are equal to one another. Confequently the figure adbe is a…
Navigation · Nautical astronomy · Fortification
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