125 (cos 288 + i sin 288) can be written as
125 ei 288 or 125 ei (288 +360) or 125 ei( 288+ 720)
To take the cube root of each of these, take the cube root of the 125 ( which is 5) and divide the argument of the exponential by 3 (raising to the 1/3 power)
This results in 5 ei 96 ; 5 ei 216 ; 5 ei 336 Now using DeMovrie (Euler formula) one gets
5 (cos 96 + i sin 96) ; 5(cos 216 + i sin 216 ) ; 5 (cos 336 + i sin 336)
