Distance between Points in Complex Plane

Theorem
Let $A$ and $B$ be points in the complex plane such that:
 * $A = \tuple {x_1, y_1}$


 * $B = \tuple {x_2, y_2}$

Then the distance between $A$ and $B$ is given by:

where $z_1$ and $z_2$ are represented by the complex numbers $z_1$ and $z_2$ respectively.

Proof
We have: