[math-fun] Power Station Problem

Imagine a power station with towers of negligible (=0)width built at the four corners of a rectangle on a flat plane. At a certain viewing point, P, on the plane, the bases of the four towers are equally spaced in viewing angle by an angle, theta. P is at a different distance from each corner and the distance from P to the closest tower is equals the length of the long side of the rectangle. For this case theta equals 90/7 degrees to 15 places of accuracy but I’m unable to prove equality. Any takers in finding a proof? Dick Hess Sent from my iPhone