Buna ziua! Doresc si eu o rezolvare urgenta la aceste probleme:
1)Stiind ca x+y+z=pi demonstrati:
sin(x/2)+sin(y/2)+sin(z/2)=1+4sin[(pi-x)/4]sin[(pi-y)/4][(pi-z)/4]
cos(x/2)+cos(y/2)+cos(z/2)=4sin[(pi-x)/4]sin[(pi-y)/4][(pi-z)/4]
2)Demonstrati ca
cos la puterea 3 de( x) + cos puterea 3 de [(x+2pi)/3]+ cos la puterea 3 de [(x+4pi)/3]= 3/4 cos de (x)
Multumesc anticipat![/code]
Multumesc mult.