1-sin^2(-x)+cos(4pi-x)=cos(x-2pi)

Question

1-sin^2(-x)+cos(4pi-x)=cos(x-2pi)

Answer 1

1-sin²x+cosx=cosx
cos²x=0
(1+cos2x)/2=0
1+cos2x=0
cos2x=-1
2x=π+2πn
x=π/2+πn,n∈z

Comments

специалист тригонометрии))