A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects (1852)
Robinson, Horatio N[elson], 1806-1867. [from old catalog] · Cincinnati, J. Ernst · leaf 20
INTRODUCTION. 15 PROBLEM 8. To find a third proportional to two given lines. Let AB and AC be any two lines. Placethem at any angle, and join CB. On thegreater line, AB, take AD=AC, and throughD, draw DE parallel to BC; AE is the thirdproportional required. Proof, (th. 17, b. 2). … PROBLEM 9. To find a fourth proportional to three given lines. Let AB, AC, AD, represent thethree given lines. Place the first twotogether, at a point forming any angle,as BAG, and join BC. On AB placeAD, and from the point D, draw(problem 6) DE parallel to BC; AEwill be the fourth proportional…
Surveying · Navigation
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