Newcomb, Simon, 1835-1909 · New York, H. Holt and company · leaf 265
lowing is the most common. We take, for positions of refer-ence: 1. A fixed plane, called the/?m^amew^aZjt??awe. For thisthe plane of XY in rectangular co-ordinates is generallychosen. 2. An origin or pole, 0, in this plane. 3. A line of reference, for which we commonly choose theaxis of X. Let P… … damcntal plane, and join 0(2. The direction of OP is then defined by the following two r^ angles: (1) The angle P0(> whichOP forms with its projectionOQ] that is, the angle be-tween OP and the plane. (2) The angle X0§ whichthe projection of OP makeswith OX. It will be remarked thatthe planes of…
Geometry, Analytic
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