When spinning at 600 rotations per minute two washing machines produce two sinusoidal forces with same maximum amplitude of 400N, but their maximum amplitudes are separated in time by 0.0125s. The two machines are placed side by side and to check their effect on a suspended laundry floor it is necessary to find their resultant vertical force. Find time-varying function describing the resultant of the two vertical forces including the amplitude and phase shift relative to one of the two excitation forces