Plane trigonometry, and its application to mensuration and land surveying. Accompanied with all the necessary logarithmic and trigonometric tables (1852)
Perkins, George R. (George Roberts), 1812-1876 · New York, D. Appleton · leaf 50
the sine of 39° 15fromthe log. of 75, it was necessary to increase this logarithm by 10, since the logarithmof the sine had been increased by the same quantity. In the second operation,after adding the log. of the cotangent to the log. of 75, we rejected 10 from thesum, for the reason assigned in… … 4:0 TRIGONOMETRY. [CHAP. in. By definitions (§ 8), we have which give cos. A = -7-; tang.A = ^r, A= ——r-. .... (1.) cos. A J p = h tang. A (2.) Using logarithms, we have log. h = log. J—log. cos. A. . . (3.)log. p = log. 5 + log. tang. A. . . (4.) For example, suppose the base to be 90*5, and the…
Plane trigonometry · Surveying
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