Definition:Lemniscate of Bernoulli/Major Semiaxis

Definition

Consider the lemniscate of Bernoulli defined as the locus $M$ described by the equation:

$P_1 M \times P_2 M = \paren {\dfrac {P_1 P_2} 2}^2$

where $O$ is the point at the center where the branches cross.

Each of the lines $O P_1$ and $O P_2$ is a major semiaxis of the lemniscate.