32O Note relative to the comparison of Arcs of Curves. 



TP, TT will be equal to the difference between the arts AT, 

 AT'. 



These properties give the readiest and most elegant solution 

 of problems concerning the comparison of different arcs of a 

 plane or spherical conic. Any arc being given on" a conic, we 

 may find another arc beginning from a given point, which shall 

 differ from the given arc by a right line if the conic be plane, 

 or by a circular arc if the conic be spherical. 



