wave with labels A, B, C, and D—labels correspond to the following: A—amplitude, B—wavelength, C—crest, and D—trough Wavelength - The distance from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough. Crest - The highest point of a transverse wave above the equilibrium position. Trough - The lowest point of a transverse wave measured from the wave's equilibrium position. Amplitude - The distance from the equilibrium position of a transverse wave to the top of a crest or the bottom of a trough. Amplitude - The distance from the equilibrium position of a transverse wave to the top of a crest or the bottom of a trough. Wavelength - The distance from the top of a crest to the top of the next crest, or from the bottom of a trough to the bottom of the next trough.