?.2I'JThe following equation describes the peat pattern. E = 159.com\"; mgr} maria: an Derive a different version of that expression assuming that the two overlapping equalamplitude cosine waves have angular spatial frequencies of ice + M: and k; at, and angular temporal frequencies of can + ora and (an dam, respectively. Here kc and ma correspond to the central frequencies. Show that the resultant wave is E = ZEN cosikx - Amt} cosIkcx wrl'} Explain how each term relates back to E = 2Egl Cos (kmx - w/) cos (kx - wt) Prove that the speed of the envelope, which is the wavelength of the envelope divided by the period of the envelope, equals the group velocity, namely, AAk. (3 points)