



,
,
=
=
=
=






.
The reference angle for
is 60° and since x is - and y is +,
is in the 2nd quadrant, so we subtract 60° from 180° and get
120°, which has the same trig functions as 120° + 360°·k, so we take:


.
Now we have






Now we use the formula: 





Now we let k = 0,1,2,and 3 to get the 4 4th roots, the 4 possible
answers for z:
For k = 0,


For k = 1,


For k = 2,


For k = 3,


Those are the four values for z.
Edwin