An elementary treatise on analytical geometry : embracing plane co-ordinate geometry, and an introduction to geometry of three dimensions (1869)
Johnson, William Woolsey, 1841-1927 · Philadelphia : J.B. Lippincott · leaf 113
th a parabola, we shall use for the equation of thestraight line the form X = nY -f- a, in which, X and Y are co-ordinates referred to the ver-tex and axis of the curve,and n is the cotangent ofthe inclination of the line(Art. 46). Substituting thevalue of X, in the geomet-rical equation, Yf=2pX,… … SECANT AND TANGENT LINES. 109 X = n2p -f a ± n\/ny -\- 2pa. When the radical V n2pl -J- 2pa is real, the line is a secant, asPP in the figure; and the rational parts of the above values are theco-ordinates of M, the middle point of the chord PP. The ordi-nate of M is therefore np; it is independent…
Geometry, Analytic
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