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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?