In the given you wrote -2, whereas it should be -2i
z = a + bi and in trigo form | z |.(cos Ф + i.sin Ф).
z = 0 -2iĀ ā | z |.(cos Ф + i.sin Ф)
Now let's calculate z:
Ā
z² = a²+b² ā z² = 0² (-2.i)² ā z = -2(i)² āz= -2(-1)Ā ā z = |2|
tan Ф = b/a = -2/0Ā ā tan Ф ā -Ā āĀ ā Ф = -90° or Ф = 270°
Ā then the - 2 IĀ ā |2|(cos 270° + i.sin 270°)