This image represents points (x,y) that satisfy the equation:

π
/4 = tan^{-1}(y_{1}/x_{1}) +
tan^{-1}(y_{2}/x_{2}).

The image is made up of zillions of circles. For each circle, the points
(x_{1},y_{1}) and (x_{2},y_{2})
are the endpoints of the diameter.

© 2013 Kerry Mitchell