A company designed and sells an ultrasonic receiver, which detects sounds unable to be heard by the human ear. The receiver can detect mechanical and electrical sounds such as leaking gases, air, corona, and motor friction noises. It can also be used to hear bats, insects, and even beading water. The receiver is 2121 in. deep. The focus is 7 in.7 in. from the vertex. Find the diameter of the outside edge of the receiver.
