Two sinusoidal waves, identical except for phase, travel in the same direction along a string, producing a net wave y'(x, t) = (3.20 mm) sin(42.0x - 5.40t + 0.940 rad), with x in meters and t in seconds. What are (a) the wavelength of the two waves, (b) the phase difference between them, and (c) their amplitude ym? (a) Number i (b) Number Units Units (c) Number Units