Bailey, Frederick H. (Frederick Harold), 1865- · Boston, London, Ginn & Co. · leaf 194
bola. Proceeding in this way we may determine as many jointsof the curve as we wish. (2) By a mechanical device. As before, F (Fig. 78) shall be the focus and DDthe direc-trix. ACB is a triangle, right angled at C, which moves withCB always coinciding with DD. A thread of length equalto AC is… … Fig. 78. 83. Angular Properties of Tangent and Normal. 1. The tancjent viakes equal angles with the focal radiusdrawn to the iwint of contact and the axis of tlie -parabola. In Fig. 79, let PjT be tangent at the point Pi (xi, yi) to theparabola y^ ^=- 4px, of which the focus is F. We have then…
Geometry, Analytic
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