MA THEM A TICS 



33 



MENSURATION 



MEANINGS OF SYMBOLS 



In the following formulas, the letters have the meanings 

 here given, unless otherwise stated: 

 D = larger diameter; 

 d = smaller diameter; 

 R radius corresponding to D ; 

 r = radius corresponding to d\ 

 p perimeter or circumference ; 

 C = area of convex surface = area of flat surface that can be 



rolled into the shape shown; 



5 = area of entire surf ace = C+ area of the end or ends; 

 A = area of plane figure ; 

 IT = 3. 1416, nearly = ratio of circumference of any circle to 



its diameter; 

 V = volume of solid. 

 The other letters used will be found on the illustrations. 



TRIANGLES 



Using letters to denote the angles, 

 D =B+C 

 B =D-C 



E' = E B' = B 



For a right triangle, c being the hypotenuse, 



If c = length of side opposite an 

 acute angle of an oblique triangle, 

 and the distance e is known, 



-2be 

 h 



If c = length of side opposite an obtuse angle 

 of an oblique triangle, 



