A whispering chamber is an elliptically arched chamber. A unique feature of a whispering chamber is that when a person standing at one focus of the ellipse whispers, he can be heard by a person standing at the other focus, regardless of the dimensions of the ellipse from which the dome is built. Suppose that the dimensions of the ellipse used to create a whispering dome is 180 feet by 420 feet. Angela stands at one focus, and Zach stands at the other focus. How far apart are Angela and Zach? Enter your answer, rounded to the nearest tenth of a foot, in the box.