The ship in the figure below travels along a straight line parallel to the shore and a distance d = 580 m from it. The ship's radio receives simultaneous signals of the same frequency from antennas A and B, separated by a distance L = 700 m apart. The signals interfere constructively at point C, which is equidistant from A and B. The signal goes through the first minimum at point D, which is directly outward from the shore from point B. Determine the wavelength of the radio waves.