The elements of plane analytic geometry. A text-book including numerous examples and applications, and especially designed for beginners (1903)
Briggs, George R. (George Russell), b. 1853, Bôcher, Maxime, 1867-1918 · New York, J. Wiley & sons; [etc., etc.] · leaf 62
inQ and Q, respec-tively, ^/^i, perpen-dicular to A B, measures the required distance of P^from A B.In the figure, O Q =p and XO Q = a. We have chosen p, measured from O to Q, positive; this is,therefore, the positive direction of lines parallel to O Q. Since (i) and (2) are parallel lines, the… … THE STRAIGHT LINE. 55 Now, P^ is a point of the line (2) ; therefore its coordinatesmust satisfy equation (2), and we have x^ cos a^- y^ sin a =/. Substituting this value of/ in equation (3), we have R F^ — x^ cos a + j^ sin a —/, (4) which expresses the required distance in terms of known…
Geometry, Analytic -- Plane
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