[ 575 ] 
— -a — « "a nd P 6^x COxC K' xCIT, Sec. = 
2 n oo x V w 2 + c z x "v/ft) 2 -b d' 2 , Sec. when n is an 
even number ; O P n — 0 will then be — n x 
x C O x C X' x C K", &c. where the diameter P 
n 
2 
takes place inftead of the infinite quantity C K. 
But if n be an odd number, OP * — O will be 
= 2 x CO x CX' x C X" x CK"\ Sec, 
XI. 
It is evident that, of the factors C K', C K\ C K", 
Sec. the firft and laft, the fecond and laid but one, &c. 
are refpedtively equal to each other. Therefore, 
omitting the fquares of the fadtors below P ^ and 
the fquares of their values, 
O^-OCi s = 72 X P^xCOx cr X CK' 1 x 
n n 
C K See. and a -f- co — a — w = 2 a ?i w x c z 
x a> 2 + d 2 , &c. when n is an even number ; or 
OP” — 0 Jjb is = 2 xC 0 xCX' 2 x CK" 1 x CK!"\ 
n _____ n . 
Sec. and a + &> « — a — &> = 2 a iXwO^b^-f ^ 
Sec. when n is an odd number. 
XII. 
X 
If we fuppofe y = — i, and n an odd number, it 
will appear, by proceeding much in the fame manner 
VI « » 
as in VIII. that a 4- -j- 2 x w 
M is = n z x x co 2 + b z x w 2 -j- x co 2 + 
Sec, 
