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Our posts crossed.I wrote my formula down a bit wrong, where I said diameter, I meant circumference. Dunces cap on. Yes, number of pitches is 4. Pitch is 1/4 of the length of the cylinder, = 3
Formula: length of string = n x square root of (circumference squared + pitch squared
L = 4 x square root of (4 squared + 3 squared)
L = 4 x root 25 = 20.
And I was not gonna do hard sums this week ---------
NOW we get it!
And it happens to be exactly the same as my hypoteneuses of my small rectangles added together.
Don't you think my ways of doing it are just a bit more elegant though?
The Cross of Saint Andrew comes in handy for visualising it!