16.5 Exercise 9

Two sinusoidal waves are moving through a medium in the same direction, both having amplitudes of 3.00 cm, a wavelength of 5.20 m, and a period of 6.52 s, but one has a phase shift of an angle $\phi$. What is the phase shift if the resultant wave has an amplitude of 5.00 cm? [Hint: Use the trig identity $\text{sin} u + \text{sin} v = 2 \text{sin} \left(\frac{u + v}{2}\right) \text{cos} \left(\frac{u - v}{2}\right)$