Two identical speakers 10.0 m apart are driven by the same oscillator with a frequency of f = 21.5 Hz (Fig. P18.12)
(a) Explain why a receiver at point A records a minimum in sound intensity from the two speakers.
(b) If the receiver is moved in the plane of the speakers, what path should it take so that the intensity remains at a minimum? That is, determine the relationship between x and y (the coordinates of the receiver) that causes the receiver to record a minimum in sound intensity. Take the speed of sound to be 344 m/s.

9.00 m 100 m Figure P18.12