Any Sound from One Focus of an Ellipse Reflects Off

Multiple Choice

Any sound from one focus of an ellipse reflects off the ellipse directly back to the other focus.This property explains whispering galleries such as Statuary Hall in Washington, D.C.The whispering gallery shown in illustration has the shape of a semi-circle.Find the distance sound travels as it leaves focus F and returns to focus F'.Round your answer to one decimal place, if necessary. ​ ​

A) 16 meters
B) 16.8 meters
C) 33.5 meters
D) 32 meters
E) 31.2 meters