Plane and solid analytic geometry; an elementary textbook (1904)
Ashton, Charles Hamilton, 1866-1936 · New York, C. Scribner's Sons · leaf 30
always satisfy himself thatthere is no restriction on their position, and that, if anyother figure is constructed and lettered in a correspond-ing way, just the same demonstration will hold letterfor letter. Oh. II, § 12] THE POINT 13 12. Distance between two points in oblique coordinates. —When… … Fig. 13. Fig. 14. directions will be the same as the positive directions ofthe axes. The angle between them will always be a>,and the generalized form of the law of the cosines(Art. 7) gives PXP2 = Vp2jf2 + jzpf + 2 P2K- KPX cos *», where not only the magnitudes, but also the directionsof the…
Geometry, Analytic
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