I.* lo,; j 



TOE II ) i 



D tli.- .-, jii.it:-.!; . i_## , j f 



a* '- 

 .ntcroept 01 tangent i* 





the lenth of 



Now, in the t: / 1\ 



/'/10 







77 



- 



,- 



/' / 



fa, 

 -a. 



[Art. 161] 



nee 



/ / 7T, 



and, by elementary geom.-trv. tlie tangent bisects internally 



ingle between tlu- final radii. Tln-n. since the normal is 



1 u t.. the tangent, the nurm.il P % N bbecto the 



i ml angle FJ\ W. Theae facU suggeat a method, anal- 



