00:01
Okay, so we want to find the cube root of negative 8i.
00:05
So if we're finding our cube roots, we want to have n be equal to 3.
00:09
And we also want to rewrite our negative 8i in chig form.
00:13
So this is going to be 8c of 90.
00:17
Actually, we want this to be negative.
00:19
So that's 270 degrees.
00:22
Okay, so let's use our nth root theorem.
00:24
So that's going to be the third roots of r, which is 8.
00:27
And then we have cis of alpha.
00:29
So that's equal to 2, cis, of.
00:31
Alpha or alpha is equal to data that's 270 degrees plus 360 degrees times k over our n value which is 3 so what's 270 divided by 3 that's 90 degrees plus 360 divided by 3 which is 120 degrees times k and this is 4k equaling 0 1 or 2 so now 1k is equal to 0 our first root that's going to be 2 cis of 90 degrees...