Réponse :
z = (cos 4π/9 + i sin 4π/9)/(cos π/9 + i sin π/9)
cos 4π/9 + i sin 4π/9 = e^i4π/9
cos π/9 + i sin π/9 = e^iπ/9
e^4π/9/e^π/9 = e^i(4π/9 - π/9) = e^i3π/9 = e^iπ/3
e^iπ/3 = cos π/3 + i sin π/3 = 1/2 + i √3/2
forme exponentielle de z = eiπ/3
forme algébrique de z = 1/2 + i√3/2
Explications étape par étape
