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 20
note the length of the arc whichmeasures this angle ; also let the an-gle CAD be denoted by o ; then willBAD be denoted by a-\-o. Draw EF perpendicular to AC, andfrom the points E and F draw EGand FH perpendicular to AB; alsodraw FK perpendicular to EG. Since the sides of the triangleEFK are… … AE AE AE HF AF KE EF AFXAE + EF XAE* 10 TRIGONOMETRY. [CHAP. I. HF AF KE By our definitions (§ 8), -^—r = sin. a ; -r-g = cos. b; ^ cos. a; EF AE sin. b. Hence, we have sin. {a-\-b)~ sin. a cos. b + cos. & sin. &.Again, we have , .., xx AG AH-KF AH KF AE AE AE AE AH AF KF EF x...-.. . ,…
Plane trigonometry · Surveying
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