COT? 



S P or = - , where / traced out by 



1 4. cos. o 



2 cos.* 4 

 rad. vect. S P. 



Ch. curv. = 4 S P. 



Diain. curv. = 



Equation to the curve # 2 a x (a L). 



JVofe. The general equation to a parabolic curve is a 1 ~ y x n ' 

 If n = 3, it is called the cubical parabola. 

 If n = , it is called the semi-cubical parabola. 



ELLIPSE! 

 SP-fPHr=2AC. 



A S. S M = B C 2 . 



S P. P H = C D 2 . 



A C 2 + C B 2 C P* + C D 8 . 



A C. C B = C D. PF, or if the perpendicular P F be called P.. 



52 _ fi s 



Pv. vG X CD 2 



B C a V i e , where e eccentricity =r , 



- ___ 



^ (I e 2 COS .S g) V 1 C 2 COS.* 



p _ Af __ !_ __ _ a (1 e) 

 a ' 1 + e cos. 1 4- e cos. ^ ' 



Ch. curv. through centre = - _, 

 c * 



66 



