Plane and solid analytic geometry; an elementary textbook (1904)
Ashton, Charles Hamilton, 1866-1936 · New York, C. Scribner's Sons · leaf 154
gles are also equal in the figure ? Note. — Parabolic reflectors depend on this principle. If a surface isformed by revolving a parabola about its axis, all waves of light, etc.,which start from the focus will be reflected in lines parallel to the axis ofthe parabola. 5. Two parabolas which have… … Fig. 74. The coordinates of any point L on the directrix maybe represented by ( — —, yA. The equation of PXPV thechord of contact of tangents from this point, is yxy = mx m? y = lx + m21 X ml y = ~T ~ ~2 138 ANALYTIC GEOMETRY [Ch. X, § 78 Since the coordinates of the focus (—, 0 J satisfy this…
Geometry, Analytic
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