[ 354 ] 
= h = / ~ *x+wo ~ 4 // _ ±tt q= /7 d=WZ£vz 
V 21/ 1/ ‘ ~ v —) 
_ . 2 P‘ . * + « 
V 
-T- 2** 
> 5 = 
> z = X v 
V — p 
dr b -t- z 
Hence />rr : X v\ v — _ , ^ 
i z-j-i/ -1-# ± z — 
Therefore p is lefs than, equal to, or greater than ± // + z, in the Ellipfis, Para- 
bola, or Hyperbola. 
67 . Draw mp., making the z. PWftr l. pcm, and cutting pc in f*. 
rTPL /pmXp m * cc Z <u tt — Q)S)XX 
Then p^ = ( — ) — — — Yr — 
' FC T \tt ± cc qr itn Vcc + l Pf , /r^ 
~ p = | parameter to pc. 
68. Let be an ordinate to the axis A a. at the focus F. and $G a tangent 
to the curve in <i>, meeting A a, bc, an, an , in G, £, s, r. Then 
= V“ X A,« =V" X « =) = 
/r tt t t 
i parameter to a 
//■ 
1 1 _ff-±zec _ 
69. C 0 _ 7 - f - v — - 
70. FG — (CGCOCF = jC n f 
tten/f cc pt 
Z ~T ~ f~ 7- 
71. Draw ph parallel to aa; and gh perpendicular to a*, meeting, ph, pt, 
in h, h ; then 
PH: 
tt t t 
DG“(CG CODC = )j: cnx—y Z = ~J X PF. 
72 . TG 
