HSSC Forge / Maths 11th / Complex Numbers / Cube Roots of Unity

Cube Roots of Unity

The cube roots of unity are the solutions to z3=1z^3 = 1. Factoring z3−1=(z−1)(z2+z+1)=0z^3 - 1 = (z-1)(z^2+z+1) = 0 gives one real root and two complex ones:

z=1,ω=−1+i32,ω2=−1−i32z = 1, \quad \omega = \frac{-1+i\sqrt{3}}{2}, \quad \omega^2 = \frac{-1-i\sqrt{3}}{2}

ω\omega is usually called the primitive cube root of unity — the other two roots, 11 and ω2\omega^2, can both be written as powers of it.