Ready to run around in circles?

Four circles radius 4, centers (4,9), (28,9), (16,4), (16,18),

are each tangent to one side of an isosceles trapezoid.

All four tangent points are situated at middle of each side.

Gimme the trapezoid's side lengths (the one with height=6).

If you wish, you could try the possible trapezoid(s) that contain

the four circles.