Definition:That which produces Medial Whole with Medial Area/Annex

Definition
Let $a, b \in \R_{>0}$ be (strictly) positive real numbers such that $a > b$.

Let $a - b$ be a straight line which produces with a medial area a medial whole.

The real number $b$ is called the annex of the straight line which produces with a medial area a medial whole.