Mathc initiation/Fichiers c : c77cx2

Sommaire

Application de cos(x)cos(y) 

             /
 Etudier:   | cos(ax)cos(bx) dx = 
            /
                                          ________________________________________________
                                         | cos(ax)cos(bx) = 1/2 [cos(ax-bx) + cos(ax+bx)] |
                                         |________________________________________________|
              
             /                     /
      donc  | cos(ax)cos(bx) dx = | 1/2 [cos(ax-bx) + cos(ax+bx)] dx
            /                     /
                 
                                       /                   /
                                = 1/2 |  cos(ax-bx) + 1/2 | cos(ax+bx)  dx                          
                                      /                   /
                                      
                          *****************            

             /                           /                   /
 Exemple:   | cos(3x)cos(2x) dx = = 1/2 |  cos(3x-2x) + 1/2 | cos(3x+2x)  dx
            /                           /                   /
                                       
                                       
                                         /               /       
                                  = 1/2 |  cos(x) + 1/2 | cos(5x)  dx    
                                        /               /