72. Fluctuating point away from the source of vibrations at a distance of 0.5 and 1.77 m in the direction of wave propagation. The phase difference between their oscillations is 3π / 4. The oscillation frequency of the source of 100 s-1. Determine a wavelength, and its propagation velocity.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)