a-ain on tlie left of A ; and as j denreases, p and 0 move towards A, until wlien -j = 0, tliev co- incide with A. Thus as the ratio changes, P and Qalways move in contrary directions; and as p movesfrom B to A, Q moves from B to the right to infinity,reappears from infinity at the left of A, aiid… … For ABBC AD , , AB dc^^bc —-, from similarCX BAO, BCX; ah AD —, from similar AS DAO, DCY; DC.. CX-CY. The consti-netion for the harmonic division of a line(Prop. 23) would have suggested the truth of the pre-ceding, sinee XA, XP, XB, XQ form a harmonicpencil. . 262 Geomeiky. Prop. 25. If A, B, C, D…
Geometry · Geometry, Plane
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