A treatise on surveying and navigation: uniting the theoretical, practical, and educational features of these subjects (1857)
Robinson, Horatio N[elson], 1806-1867. [from old catalog] · Cincinnati, J. Ernst; Toledo, Anderson, Burr, & co. · leaf 207
or E=-£ Q. E. D. Another Demonstration.—The angle x being the half of A CD is equal to A+2y 2The angle x is also equal to E-\-y, because it is the exterior angleto the triangle EBC.Therefore, by equality, 2Whence, E=\A Q. E. D. 204 CELESTIAL OBSERVATIONS. … We are now prepared toshow the construction ofthe sextant and quadrant. The instrument repre-sented by the annexed cutis a quadrant or a sextant,according as the arc con-tains 90° or 120°, but eachactual degree of arc isgraduated to 2°, and thespace that covers 90° isreally but 45°, and so on. The…
Surveying · Navigation
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