LISE780
Answered

Help ! Calculer de 2 manières différentes : cos(3PI/2 + PI/3) cos(PI/3)+ sin(3PI/2 + PI/3) sin(PI/3)  merci d'avance !

Sagot :

cos(3π/2 + π/3) cos(π/3)+ sin(3π/2 + π/3) sin(π/3)

=cos(π/3-π/2)cos(π/3)+sin(π/3-π/2)sin(π/3)

=sin(π/3)cos(π/3)-cos(π/3)sin(π/3)

=0

 

cos(3π/2 + π/3) cos(π/3)+ sin(3π/2 + π/3) sin(π/3)

=(cos(3π/2)cos(π/3)-sin(3π/2)sin(π/3))cos(π/3)+(sin(3π/2)cos(π/3)+cos(3π/2)sin(π/3))sin(π/3)

=sin(π/3)cos(π/3)-cos(π/3)sin(π/3)

=0