Young, George, jr, Baxter, Hubert Eugene, joint author · New York, Macmillan · leaf 151
irstmethod. In Fig.128, let a be thegiven point oftangency. Drawah perpendicular tothe axis. Lay offvc equal to vb. Therequired tangent isthe line ca.y Second method,using the focus.Let d be the re-quired point oftangency. Thefocus, /, can be de-termined by § 117.Lay off vz=vf, anddraw the… … Fig. 128 128, be the given point. With Let s. Fig.s as a center and «/ as a VII, § 1-20] CURVED LINES 133 radius, draw a circle tfw intersecting the directrix at t and w.Perpendiculars to the directrix drawn from these points willintersect the parabola at q and u which are the required pointsof…
Geometry, Descriptive
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