Can some please check my answer.

Question

z4k4r1y4 · Answer

What phase difference between two otherwise identical traveling waves, moving in the same direction along a stretched string, will result in the combined wave having an amplitude 0.94 times that of the common amplitude of the two combining waves? Express your answer in (a) degrees, (b) radians, and (c) as a fraction of the wavelength.

z4k4r1y4 · Answer

(a) 123.93 degrees
(b) 2.163 radians
(c) 0.34425

michele_laino · Answer

the answers a), and b) are correct, since if I call with $A$ the amplitude of a single wave, then the phase difference $\varphi_0$, is given by the solution of the subsequent equation:
$$2A\cos \left( {\frac{{{\varphi _0}}}{2}} \right) = 0.94A$$

z4k4r1y4 · Answer

for (c) I did 2.163/2pi

michele_laino · Answer

yes! it is correct!  I got the same result, solving this proportion:
$$\Large \lambda :2\pi  = x:{\varphi _0}$$

z4k4r1y4 · Answer

thank you. I really appreciate the help.

michele_laino · Answer

:)