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 57
sin. C _ tang, i (B + C) (1.) sin. B — sin. C tang, i (B— C) Hence, we have b+c_tang. HB + C)&-c~tang.f(B-C) (2.) or. b + c : b-c : : tang. \ (B + C) : tang. J<B-C). (3.) THEOREM III. If from an angle of a planetriangle a perpendicular bedrawn so as to meet the oppositeside or base, the… … (1.)(2.) §50.] TRIGONOMETRY. 4:7 or Subtracting (2) from (1), we have tf-a? = AD3 -BD2, (5 + a) (b - a) = (AD + BD) (AD - BD), . (3.) which, converted into a proportion, will give, observing thatAD + BD = & c:h+a:: o-a : AD-BD. (4.) K the triangle has an obtuse angle, then the perpendic-ular…
Plane trigonometry · Surveying
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