Veblen, Oswald, 1880-1960, Young, John Wesley, 1879-1932 · Boston, New York [etc.] Ginn and Company · leaf 306
\ =h 0. The line (10) will now be identical with the polar of (8) for any point (x[, x£, 0) satisfying the condition x2 a2x2 This quadratic equation must have only one root if the self-polar figureis to be of Type III This requires b2= a2, and as b2, a2 cannot bothbe 0 unless (9) degenerates, the… … and no other points. Since x3 = 0 is a tangent, this gives two common points. If the second common point is taken A = ll 00} a-fooil to be (0, 0, 1), the set of . . Fig. 102 conies which have in com-mon the points (0, 0, 1) and (1, 0, 0)=A and the tangent a at A,and no other points, may be written…
Geometry, Projective
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