WELCOME TO THE FIFTH ROOTS OF EIGHT!

HERE'S HOW YOU FIND THEM:

(8+0i) has length (magnitude) 8 and an angle to the x-axis, or modulus, of 0 degrees;
so the root circle has radius 8^1/5 = 1.516,
the first root is at theta1 = 0/5 = 0 degrees,
and the remaining root is at theta = 0 + n*360/5 = 72, 144, 216, and 288 degrees.