In mathematics, two-center bipolar coordinates is a coordinate system, based on two coordinates which give distances from two fixed centers, C1 and C2  This system is very useful in some scientific applications It should not be confused with so-called bipolar coordinates. Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and two-center bipolar coordinates Bipolar coordinates are a two-dimensional orthogonal Coordinate system.
Transformation to Cartesian coordinates from two-center bipolar coordinates 
where the centers of this coordinate system are at (+a, 0) and (-a, 0).
To polar coordinates from two-center bipolar coordinates
Where 2a is the distance between the poles (coordinate system centers).