z = 1 - i√3 ⇒ punctul P ( 1 , - √3) in cadranul IV
tg α = - √3 /1 = - √3 ⇒ α =5π/3
IzI = √1²+(-√3)²=√1 +3 = √4 = 2
z = 2 ( cos 5π/3 + i sin 5π/3 )
radacinile de ordinul 3 cu k =0,1,2
∛z = ∛2 [ cos ( α + 2kπ) /3 + i·sin(α + 2kπ)/3 ]
k=0 z₁ = ∛2 [ cos 5π/9 + i·sin5π/9 ]
k=1 z₂ = ∛2 [ cos ( α+2π ) /3+ i·sin(α+2π) /3 =∛2 ( cos 11π/9 + i·sin11π/9)
k=2 z ₃= ∛2 [ cos(α+4π)/3 + i·sin(α+4π)/3 ]= ∛2 ( cos17π/9 + i·sin17π/9)
