00:01
Here i want to find the cube roots of z, the cube root of negative 1 plus i.
00:08
First step, draw this on an organ diagram.
00:14
And i want the answer is impolar form.
00:16
So write this impolar form first.
00:20
Here is negative 1 plus i.
00:22
So negative 1 is that coordinate point.
00:26
The angle here is 3 pi by 4 or 135 degrees.
00:34
Because down here would be 45 degrees of pi by 4.
00:40
So, z then, is equal to the length of this line, which by pythagoras is simply root 2, e to the i, and the angle is 3 pi by 4.
00:55
That's z.
00:57
Now, i could also write that in more general terms as root 2, e to the i, 3 pi by 4, plus 2n pi.
01:11
Keep adding on 2 pi, i get the same result.
01:15
So that means if i want to work out the cube root of z, i take root 2, e to the i 3 pi by 4 plus 2n pi.
01:33
And we need, of course, brackets here.
01:35
Let's put those in...