Ziwet, Alexander, 1853-1928, Hopkins, Louis Allen, joint author · New York, The Macmillan company · leaf 115
hree. 104. Geometric Properties. Let the tangent and normalat P (Fig. 69) meet the axis at T, N; let Q be the foot of theperpendicular from P tothe axis, D that of the per-pendicular to the directrixd; and let O be the vertex,F the focus. As the subtangent TQ isbisected by 0 (§ 98) andthe subnormal… … KiQ. 59 VI, § 105] THE PARABOLA 105 Hence, if axis and focus are given, the tangent and tlie normalat any point P of the parabola are found by describing aboutF a circle through P which will meet the axis at T and N. Aa FP=DP, it follows that FPDT is a rhombus; thediagonals PT and FD bisect…
Geometry, Analytic
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