z⁵ = - i = 0 - i
punctul A ( 0 , - 1) ⇒ α =270° = 3π /2
| 0 - i | = √( -1)² = 1
z⁵ = cos3π/2 + isin3π/2
rad . z = cos ( 3π/2 +2kπ ) / 5 + isin ( 3π/2 + 2kπ ) / 5
k= 0,1,2,3,4
k=0 z₀ = cos3π /10 + isin 3π/10
k=1 z₁ = cos ( 3π /2 + 2π ) /5 + isin( 3π/2 + 2π) /5 =
= cos7π /10 + i sin 7π/10
k =2 z₂ = cos ( 3π /2 + 4π) / 5 + isin( 3π/2 + 4π ) /5
= cos11π /10 + isin11π/10
k=3 z₃ = cos 3π/2 + i sin3π /2
k = 4 z₄ = cos 19π / 10 + isin19π/10
