text: a~= 18.24 &  (degrees) 
  (  ) 
  
  the derivation of these relationships 
  (NOTE: 
  may be found in any of the standard engi- 
  neering aerodynamics textbooks.) 
  
  These relationships facilitate an understanding 
  and appreciation of induced drag. 
  
  The induced angle of attack Eli= 18.~4$~ 
  ( 