An elementary treatise on coordinate geometry of three dimensions (1912)
Bell, Robert J. T. (Robert John Tainsh), 1877-1963 · London : Macmillan and co., limited · leaf 39
efore that the projections of AB and BAdiffer only in sign. It is evident that AB is the intercept made on XX bythe planes through A and B normal to XX, and hence theprojections of equivalent segments are equivalent segments. 14. If AB is a given segment of a directed line MNwhose positive… … Fig. 13. Fig. 14. Draw OQ from O in the same direction as WIN, If AB< ispositive, cut off OP, the segment equivalent to AB; thenthe projection of AB = the projection of OP, = OP. cos 0, (by the definition= AB. cos 0. of cosine), If AB is negative, BA is positive, and thereforethe projection of…
Geometry, Analytic
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