Veblen, Oswald, 1880-1960, Young, John Wesley, 1879-1932 · Boston, New York [etc.] Ginn and Company · leaf 161
, from similar triangles, the Pr°POrti0nS: PqP^Pq^PqP, PoPy PqY PoPxy which, on taking the segment P0Pi = 1, gives the desired result PaPxy=PoPx PoPy 146 ALGEBKA OF POINTS [Chap. VI Corollary 3. The operation of multiplication is associative; i.e. wehave (Px ■ Py) ■ Pz = Px ■ (Py ■ Pz) for every… … P> Pi i% ti *y -*iy *y* *fry)*~H^t) ■*» Fig. 70 as in the definition by means of three fundamental lines l0, lv lx,the point Pxy being determined by the line XY. Denote the line PXYby l[, and construct the point Pxy- Pz = (Px- Py) ■ Pz, using the lines l0, l[, lxas fundamental. Further, let the…
Geometry, Projective
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