The elements of applied mathematics including kinetics, statics, and hydrostatics (1894)
Jessop, C. M. (Charles Minshall), 1861-1939 · London, New York, G. Bell and Sons; [etc.] · leaf 19
g rule with regard to the sign of the pro-jection of a line should be carefully observed, viz. that aprojection MN measured from left to right as in fig. (i) istaken to be positive, while a projection measured from rightto left, as in fig. (ii), is taken to be negative. This maybe also stated thus,… … A / Fig. i. Let PQRS be a polygon, draw Pp, Qq, Rr and Ss fromits vertices upon any straight line AB. Then we see that ps=pq + qr + rs, or, projection of P)S= proj. PQ +proj. QR + proj. RS. Notice that in fig. (ii), rs, the projection of RS, is nega-tive as stated above. THE ELEMENTS OF APPLIED…
Mechanics
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