Tanner, J. H. (John Henry), b. 1861, Allen, Joseph · New York, American Book Co · leaf 257
erating curve as it revolves; and the radius of the circle isthe distance of the point from the axis before revolution be-gins. These facts lead readily to the equation cf any surfaceof revolution, as a few examples will show. (a) The cone formed by revolving about the z-axis the line 2x + 3z = 15.… … Fig. 98. But in the a%-plane, before revolution is begun, LP is theabscissa of P and may be found in terms of the third coordi-nate, z, which does not change as P moves: by equation (1), 2 so that the equation of the path of P is ■3z) ^^f = ^ (2) But P is any point of line(1); hence equation (2) is…
Geometry, Analytic
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