Length of Median of Triangle/Proof 2

Proof
Let $\triangle ABC$ be embedded in the complex plane.


 * Length-of-Triangle-Median-Complex.png

Let $A = \tuple {x_1, y_1}$, $B = \tuple {x_2, y_2}$ and $C = \tuple {x_3, y_3}$ be represented by the complex numbers $z_1$, $z_2$ and $z_3$ respectively.

Then:

Then: