C 355 ] 
m ft tt t - ■ t "4- / g ITT r r 
72 . TG = (CTMCC = ; -W 7 = -X fu>X — \ X 
nt j m > 
t— z 
f 
„„ ,._/PDXTG f« / -t //* c 
73. oA— ( — ■ ■ .■ • — — x x/w^x -r-x/co< = ) 
V DT r m tnn n J 
tz — f f. 
— x/c»*=^===x — 
74. p« r (I£^r) ic z'ic = < x V2H = L‘ 
\ dt a fy zv — rc yji 
75 - = (p£ — PR = ) — — — -^. XC c— «rz =) 
k c a c 
g f c z c J 
WC V zi ; — cc ^. zv fyc 
76. Fir (V« +n=) 
1 n vzv — cc • fy fy 
77. Let D£ be any Ordinate to the axe a a, cutting the curve ins, 
tangent $ G in c; 
Then 
ntrr: ^ 
F<I>-|-DG CC tZ f . „ 
— — X — X — = ) Z ~ F P ~ f£. 
t f cc ' 
FG 
78. Therefore as=: af ; a s — a F j C£ = CA ; by fim. AS. 
79. df 1 rr (do- 3 — DS 3 =;D(3- + d£ x Da- — D2rr) pax a-£. 
79. Let the tangents pn, p l, to the oppofite vertices p, />, cut the 
to the oppofite vertices a ,a, in n, m, l, /. 
Then p n z=. p t ; an — al ; pn =: pi AN a l. 
For the Trapezia's PC an, />CAi, are fimilar and equal; 
And fo are the Trapezia’s pcan, p cal. 
■ 7- X /<» X. 
f* 
and the focai 
tangents an. 
Vol. LX I II. 
A a a 
81. tf 
