Sine curves of varying frequency and amplitude plotted from 0 to 2 pi. Graph of y= sin θ, y= 1/2…

Triangle ABC with sides a,b,c labeled and angles A,B,C labeled and h labeled as height.

Triangle ABC with sides a,b,c labeled and angles A,B,C labeled and h labeled as height.

"Start a trough from A. At the moment of its reflection as a crest a B, start a crest at A as shown.…

"...represents two sets of sound waves with like periods and phases but different amplitudes." -Avery…

"...represents two wave systems of equal periods and amplitudes but of opposite phases." -Avery 1895