A Treatise on Algebra Volume 2; Symbolical algebra and its applications to the geometry of positions
George Peacock
Paperback
(RareBooksClub.com, May 12, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1845 Excerpt: ...that the sum of the three sides of the triangle ABC, taken in order, is equal to c + a (-cos B + J-1 sin B) + b (--cos A-J--l sin A) =c--a cos B--b cos A + J-1 (a sin B--b sin A) = 0.t The same conclusion is expressed by saying that the symbolical sum of two sides AC and CB of a triangle ACB, taken in order, is equal to the third side AB, estimated in the direction AB, and not in the reversed direction BA. Funda-I v'i De shewn, in a subsequent Chapter, that all the mental relations of the sides and angles of triangles, upon which their equations, in Trigonometry pro-For the exterior angle at B is ir--B, and at C is It--C: and the entire perly so angle of transfer, in passing from the position ABtoCA,KZir-B-C = 'ir + A: called-forX+B+C = w. f The same conclusion follows from the proposition proved in Art. 829: for if we complete the parallelogram ACBD, then the symbolical sum of AC and AD is AB: and since AD is equal to CB and estimated in the same direction with it, it is symbolically identical with CB: it fol-lows therefore that the symbolical sum of AC and CB is AB. solution or determination, from the requisite data, will depend, and which constitute the proper science of Trigonometry, are deducible from the three equations c = a cos B + b cos A a sin B = b sin A. =ir I 835. It will follow, as an immediate consequence of the The propoproposition in the last Article, that the sum of the sides of any Artl'saw, rectilineal figure, taken in order, when estimated both in position extended to... any recti and magnitude, is equal to zero: for if ABODE be any recti-lineal lineal figure, then the sum of the consecutive sides AB and BC fisule is the line formed by joining AC: the sum of AC and CD, or of AB, BC, and CD is the line formed by joining AD: the sum of AD...