



 
Hi John. Not only does it look like a graph, it looks like a perfect graph of cos(x) ! In our diagram D is the diameter of the tube and since the cut is at 45 degrees the length of PQ is also D and thus the amplitude of the cosine function is D/2 = R, the radius of the tube. The number of cycles is exactly one (once around the tube). If N is the line number from the left hand side, then
And lastly, the vertical shift depends on where you cut: it is the length from the bottom of the tube to the bottom of the cut (S) plus the amplitude. So L(N) = S  Rcos(360HN/C) where L(N) is the length of line number N, H is the horizontal spacing, C is the circumference. Hope this helps,  


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