Réponses

  • Utilisateur Brainly
2013-04-16T18:35:20+02:00

(cos(x+ pi/4))(cos(x-pi/4))+sin(x)^2

=(cosx*racine(2)/2-sin(x)*racine(2)/2)(cosx*racine(2)/2+sin(x)*racine(2)/2)+sin(x)^2

=(racine(2)/2)²(cosx-sinx)(cosx+sinx)+sin(x)^2

= (1/2)(cos²(x)-sin²(x))+sin²(x)

=1/2(cos²(x)+sin²(x))

=1/2