.I/'/'/ \/,/\ 



Again, from any point between H l and //, on Z W. draw J/0 per- 

 peudicula omFat a center uh \l>; 



at radius describo MI arc cutting ' Then P it a point of the 



fur tl. ~~s 



al.l^l.. 



' 



benoe the pointo /: <hat their dUtaneec from the 



dirv the fucu are in th r.i I each it therefor*. 



according to the definition given -he conic. 



' (and the symmetrical i aid connecting 



by a urnooth curve, the conic may be plotted to any required degree 



If a<4.V. then tan a < I. ..*., <1, and the conic it an elli|. 

 I . th. .,, i , a parabola; and if a > 45, the eooie it ao hyperboU 



NOTE C 



The special cases of the conies. The locus of the second degree ennre 



at been teen to harp three speciet, according at e < I. e = 1. or > 1. 



l = 0, then, since 6 it defined by the equation 6* = a*(l - '). A = a, 



nd the curve ia an ellipse with <s|ual axes, \.r., it b a cin- case, 



im, the .1 at infinity and the focus at the center, for the equa- 



<x*rtx is * = 2. MM! the distance from the center to the 



ocus it ae (cf. Part I, Art*. 110, 116). 



