A general geometry and calculus : including book I. of the general geometry, treating of loci in a plane; and an elementary course in the differential and integral calculus (1881)
Olney, Edward, 1827-1887 · New York : Sheldon and Co. · leaf 53
angle included between two lines is tan V = ~, in which V is the angle included 1 4- aa by the lines, and a and a are the tangents of the angles which the lines make vjith the axis of abscissas. Dem.—Let MN and MN, Fig. 26, be two lineswhose equations are respectively y =: ax -^ h andy== ax-\- h.… … X D FiQ. 26. 24 THE CARTESIAN METHOD OF CO-ORDINATES. ScH.—^In applying this formula to any particular example, we may obtain two results, numerically equal, but with opposite signs. Thus, if the two lines are 3/ = 2a7 + 4, and y = 3a; — 5, and we let a=2, and a = 3, we 2—3 1 have tan V = -—,—;:, =…
Geometry, Analytic · Calculus
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