MATHEMATICS 



A = area of one end ; 

 a = area of other end ; 



area of section midway between ends; 

 / = perpendicular distance between ends. 



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The area m is not in general a mean between the areas of 

 the two ends, but its sides are means between the correspond- 

 ing lengths of the ends. 



Approximately, 





REGULAR PYRAMID 



P = perimeter of base; 

 A = area of base. 



3 



To obtain area of base, divide it into triangles, and find 

 their sum. 



The formula for V applies to any pyramid whose base is 

 A and altitude h. 



FRUSTUM OF REGULAR PYRAMID 



a = area of upper base; 

 A = area of lower base; 



p = perimeter of upper base; 



P = perimeter of lower base. 



The formula for V applies to the frustum of any pyramid. 



iD + d\ 

 \ ~2~~ / 



LENGTH OF SPIRAL 



n = number of coils; 

 / = length of spiral ; 



t = pitch. 



