306 



Now 



Then 



PRACTICAL MATHEMATICS 



z 1 = 2R cos Z 

 t/! = R sin X 



z = 2R cos 



y = R sin 

 dy = R cos dft 

 F 



cos 2 sin dQ 



FR 2 



I COS 0j 



FR 2 r 



I cos X L 



FR 2 cos 3 t 

 I cos X X 3 



FR 2 

 31 



CDS' 5 



4F 





-1 ). since I = -r 



4 



Taking a circle of 3 inches radius and calculating the values 

 of q corresponding to horizontal sections situated at distances 

 0, |", 1", etc., from the centre. 



For any section q = 



4F 



27TC 



(i-i) 



' 





