MATHEMATICS 



17 



Approximately , 



REGULAR PYRAMID 



P = perimeter of base; 

 A = area of base. 



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

 the sum of their areas. 



The formula for V applies to any pyramid whose base is A 

 and altitude h. 



FRUSTUM OF REGULAR PYRAMID 



a = area of upper base; 

 q- 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. 



LENGTH OF SPIRAL 



n = number of coils; 



/ = length of spiral; 

 t = pitch. 



PRISM OR PARALLELOPIPED 



C = Ph 





For prisms with regular polygons as 

 bases, P = length of one side X number of sides. 



To obtain area of base, if it is a polygon, divide it into tri- 

 angles, and find sum of partial areas. 



