Complex Dot Product/Examples/Size of 2+5i dot 3-i

Example of Complex Dot Product
Let:
 * $z_1 = 2 + 5 i$
 * $z_2 = 3 - i$

Then:
 * $\size {z_1 \circ z_2} = 1$

where:
 * $\circ$ denotes (complex) dot product
 * $\size {\, \cdot \,}$ denotes the absolute value function.