(a) Express the following complex numbers in Cartesian form, i.e. in the form a + bi with a, b ∈ R:
(b) Consider the following complex numbers:
Express the complex numbers z1 and z2 in polar form (z = re^iθ). Plot z1 and z2 as vectors in the complex plane. By expressing cos(θ) in terms of complex exponentials, express cos^2(θ) in terms of cos(2θ) and cos(3θ). Consider the following equation x^3 + 125 = 0. Calculate all the roots of this equation. Represent all the roots as vectors in the complex plane.