1. The problem statement, all variables and given/known data During one complete cycle, a wave moves through ___ wavelength, ___ period, __ amplitudes 2. Relevant equations 3. The attempt at a solution Well I got 1 wavelength, 1 period, and 2 amplitudes But apparently the answer is 1 wavelength, 1 period, and 4 amplitudes But I don't see how that's true. The answer even says that 2 is a common mistake, but doesn't really explain why. If in one cycle, the wave starts at the x-axis, goes up, gown down, and returns on the x-axis, wouldn't that only be 2 amplitudes?