Answer:
3 units
Explanation:
The amplitude of a sinusoidal function is the distance from the midline to the peak value. Because the function is symmetrical, it is equal to half the peak-to-peak value.
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The waveform shown has a maximum of 4 units, and a minimum of -2 units.
Amplitude = (maximum - minimum)/2 = (4 - (-2))/2 = 6/2
Amplitude = 3 . . . . units
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Additional comment
For asymmetrical or non-sinusoidal functions, the "amplitude" may have a definition that depends on the reason why the amplitude is of interest.
In audio signal processing, peaks on one side of the average value may be significantly different from the peaks on the other side of the average value. Voice wave shapes, in particular, tend to be quite asymmetrical. Since the processing equipment must be designed to avoid introducing unintended distortion, the maximum of the one-sided differences from peak to average is often the "amplitude" of interest.