\begin{definition}[Definition:Side of Rational plus Medial Area]
Let $a, b \in \R_{>0}$ be in the forms:
:$a = \dfrac \rho {\sqrt {2 \left({1 + k^2}\right)} } \sqrt{\sqrt {1 + k^2} + k}$
:$b = \dfrac \rho {\sqrt {2 \left({1 + k^2}\right)} } \sqrt{\sqrt {1 + k^2} - k}$
where:
: $\rho$ is a rational number
: $k$ is a rational number whose square root is irrational
: $\lambda$ is a rational number whose square root is irrational.
Then $a + b$ is the '''side of the sum of (two) medial areas'''.
{{:Euclid:Proposition/X/40}}
\end{definition}