[ 5^5 ] 



and therefore in this cafe the fuperficies and folid are algebraically 

 aflignable. 



Becaufe x = z s,a =: — , and y =z cs, a =\ /** ^ 

 it follows that 



«* r4 = ^2 -j- AT^ j ' is the equation to the curve in this cafe. 

 This curve will pafs through B, becaufe when « = r, /, a =- 

 radius. 



