Exercice : Exercice 26 :

Réduire les expressions suivantes :

Question

a. \(A(x) = cos(7x)sin(6x)-sin(7x)cos(6x)\)

Solution

\(A(x) = cos(7x)sin(6x)-sin(7x)cos(6x)=sin(6x-7x)=sin(-x)=-sin(x)\)

Question

b.\( B(x) = cosxcos(2x) - sin x sin(2x)\)

Solution

\(B(x) = cosxcos(2x) - sin x sin(2x)=cos(x+2x)=cos(3x)\)

Question

c. \(C(x) = cos(3x)sin(2x)+cos(2x)sin(3x)\)

Solution

\(C(x) = cos(3x)sin(2x)+cos(2x)sin(3x)=sin(3x+2x)=sin(5x)\)