Sound with a frequency 730 Hz from a distant source passes through a doorway 1.05 m wide in a sound-absorbing wall.
(a) Find the number of the diffraction minima at listening positions along a line parallel to the wall.
(b) Find the angular directions of the diffraction minima at listening positions along a line parallel to the wall. (Enter your answers from smallest to largest starting with the first answer blank. Enter NONE in any remaining answer blanks.)