z^3 = -2i => z = the three cube roots of -2i. Have you been taught how to find the three cube roots of a complex number using de Moivre's Theorem?

z^2 - 2i z - 2i = 1 => (z - i)^2 = 2i. Therefore z - i = the two square roots of 2i. Have you been taught how to find the two square roots of a complex number using de Moivre's theorem?