Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 181
ISO TRIGONOMETRY Description of Instruments, Ihe chord of the given angle aav 30 degrees, and with this lineas a radius, and B as, a. centre, describe an arc cutting BC in CThrough A and C draw the line AC, and BAG will be the re-quired angle. SEMICIRCULAR PROTRACTOR.C … 17. This instrument is used to lay down, or protract anglesIt may also be used to measure angles included between linesalready drawn upon paper. Tt consists of a brass semicircle ABC divided to half degreesThe degrees are numbered from 0 to 180, both ways; that is,from A to B and from B to A. The…
Geometry · Plane trigonometry
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