Pies INVESTIGATION of fome® 
nm—t1isa multiple of 2 by anodd number. Thus, in the en- 
neagon, or figure of nine fides, A is the cofine of 26° or’the fine 
of 70°, B is the cofine of 60° or the fine of 30°, @ is the cofine 
of ro0° or the fine of to°, and d is the cofine’of 140° or the 
PMS ei 
fine of 50, and A” —4”"—i"= — 
2 
x2, And. if p be 
any even number lefs than 2, A? + BY¢+C?+ &e. to on E 
terms oF 
os eae tab be ch &e. to se d terms, or 
“— 3 terms, (according as:7— 1 is a multiple of 2 by an even 
4 
= he Fees Pa P p 
er odd number) is s= 7x 13:8 oP ral yg ape Cah 
162. 3+4e “a 2 & 
fequently, A? ao a? + A” —a” Be + be Bu — pz ae &e. to 
—I A Tas. 50a op o rh ad rn 
4 termigy iSpy? ae ee ee a x , 
iaigigt VE ant an ee 
peo pr6 PEO... Ah 
H—_— 
. ove 
bd 
b 
ON 
ct 
° 
1 
iS 
wb 
and when n—1 is a. multiple of 2 by an odd number A’-+ A” 
n+tI 
4 
terms, + 4’—a”"-+ 
4. Bey BY + FO" + &e, to 
ae 
