[ 47 ] 



B— I 



Whence c =n\ ^ ^J" »a + n.csn — 2 a + n. ft — i cs n — 4* + &c. 



I. 2 



continued to — — terms when n is odd : but when n is even there 



n 



will be a middle term n — i- n — 2 - - ^ ^ 



1 X cs, n — 2. 2 ^ 



I. 2 - - -5 « 



« 



«. n — I - - to - tcrmi 



= J y. es a '.' in this cafe 



2. I. 2. 3 - - 5« 



r = i : X f J ;z a + „. f J /,— 2 a + &c. to ^ terms 4- ^ ^ 

 »• '^ — * - _ _ terms. 



n 

 I. 2. - - — 



2 



VII. Theorem, i. When « is any odd number, and j- the 



n—l 



fine of any arc. a, rad. being unity, s = Vi x i "f} «<»+«• J"; ^ — ^ '^ 



72. n — 1 _ n — I 



± •*■> « — 4 a 4- &c. continued to terms &c. the upper 



12. 2 ^^ 



figns taking place when n is any odd number of the form 



4/1+1, and the lower when of the form 4/) 4. 3. 



TaE 



