Jacoby, Harold, 1865-1932 · New York, The Macmillan company · leaf 216
ASTRONOMY found capable of establishing for the earth a law of planetary orbital motion first discovered by Kepler; viz. that the "radius vector" (p. 119), or line joining the planet and the … triangular area SPiP2, included be Fig. 47. Law of Areas. tween the two radii vectores SPh SP2, and the arc of the curved orbit PiP2, is equal to the other triangular area SP3P4, similarly included between two radii vectores and an arc of the curved orbit. We must now prove that this law applies…
Astronomy
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